Jeemy, I don't recall you saying anything about it?? I hope you got it for a song??
1) Most of us pros never used the " the little threading circle slot" toward the center of any reel. Just wrap the tape around the core of the reel and let friction do the job after a rotation or two. So you're doing it correctly it sounds to me?
2) If you have threaded machine properly and the tape runs out, the mechanism should disengage and the reel should come to a stop, within a very short period of time, unless you are in a fast shuttling speed such as fast forward or rewind, in which case it could take many more rotations before it comes to stop. Generally there is no problem with that other than the ends of the tape or leader tape may start looking a little ragged. Hopefully you have allowed more than just a couple of seconds of leader tape, whether it is the magnetic tape itself or a colored paper or plastic without any recording oxide on it before you start to record? The very beginning and the very end's of analog magnetic tape frequently have a greater amount of dropout and slight oxide inconsistencies.
3) The center track time code device you have was originally intended to synchronize your recorder to a videotape machine. I don't see any purpose in using it if you are simply making stereo or 2 separate mono track recordings? If anything there is risk of time code center track noise crosstalk. Time code does not sound pretty! Now if your intention is to synchronize this analog machine to your computer's multitrack audio program, so as to be able to use it for multi-track recording, so to be able to have that groovy analog sound, you would need an interface that would convert the SMPTE time code output from the synchronizer to something the computer could understand. This may only be possible with some type of computer MIDI interface that have some provisions for reading standard SMPTE time code that can then be synchronized to your software? Mark Of The Unicorn may have something like that?
4) Your Dolby 361 units are " A " type noise reduction and generally required that you encode to tape, subsequently decoding the tape upon playback. They are not what we would refer to as a " single ended noise reduction unit". There are other units made by other companies that can do just that and require no encoding but these aren't those. These particular units are not designed to be used with cassette decks. THEY ARE DESIGNED TO BE USED WITH YOUR REEL TO REEL MACHINE. They should not be ignored. They provide from 10 to 15 DB of noise reduction in 4 separate spectral bands. So the noise reduction of these professional devices are broadband. In the sense that they are reducing the inherent noise of the tape throughout the entire frequency range. This is in contrast to the Dolby button found on most cassette recorders. That is a consumer version knock off, referred to as " Dolby B and/or C and S" and those only worked primarily in the highest couple of octaves, specifically to reduce only HISS. The " C " made an attempt to also somewhat increase the dynamic range and the " S " version was an attempt to create a consumer imitation of the professional later " SR " or " Spectral Reduction ". That was Dolby's attempt to improve the objectionable qualities to the original " A " version. That version actually sounded considerably better but that is not a reason NOT to use the versions you have. Unfortunately, it must be properly calibrated to the recorder, otherwise you will get "Miss" tracking and she'll make it sound awful. So if you do not know how to calibrate them to the recorder, you should put them on eBay and deal with all the HISS analog recording has to offer. Barefoot analog is still quite lovely sounding and I never used or had any professional Dolby units in any of the studios that I have been directly involved in. 16 and 24 track machines could get pretty noisy if you're recording and mixing techniques were not up to snuff and even if they were, we still live with that little bit of HISS and continued to make lovely recordings that everybody loved.
Now there is one other purpose oriented use one can use those old Dolby 361 units for. They can make for interesting spectral compressor/processors. They provide both compression and downward expansion in 4 different frequency bands whose thresholds and levels can be independently adjusted from behind the front panel cover. Once you start playing with those controls the units will be useless as noise reduction units but can make for interesting vocal and instrumental processors as they can be used for a type of dynamic equalization and all sorts of cool things if you can't find anybody to buy them on eBay.
Now I didn't mention about how to calibrate the recorder. To do that you should have a specially produced calibrate a test tape only unavailable from a very few remaining companies. Old used test tape's might get you close but won't get you spot on. Now that's just for playback calibration.
For recording, you generally had to calibrate the machine to the specific manufacturers different kinds of recording tapes, that was different for all manufacturers and within their differences of product lines. That process requires the use of a sinewave oscillator that can reproduce the full frequency spectrum. You can get into the ballpark by utilizing the tape recorders own volume meters but it was always best to utilize an external test device such as a "VTVM" or vacuum tube volt meter, digital meter and/or oscilloscope, distortion analyzer etc.. That was the only way to obtain a truly calibrated flat response. If you don't calibrate the machine properly it will not give you a faithful recording and reproduction of what you are attempting to record.
If you are using the large 10 inch aluminum and/or plastic reels in the tape happens to be 1.5 mil in thickness and you are recording at 15 inches per second, then one half hour is what you get. Those are generally 2500 foot reels. There is also a version that is only 1.0 mil. That would yield 45 minutes at an increase of " Print Through", which were faint pre-and post echoes that you could hear during a quiet portion of a louder previous or later section of sound. It was quite annoying and was less a problem with the thicker but shorter running time tapes. The thinner tapes were 3600 foot reels.
Proper head alignment is a whole other issue but I would rather not go into here.
Grease pencil and razor blades along with a specific splicing tape and not Scotch tape was also a necessity along with something referred to as a " splicing block" which that machine, depending on the age, may have built in?
Analog editing is fun!
Ms. Remy Ann David