Hey guys need your expert opinion. I've stumbled across a Neumann 1970's era U87,.. now the grill is a bit beat up and it is 30 years old. .are there any concerns or "red flags" I should be on the look out for with a mic this old?. He's asking 1,600 for it is this a fair asking price?...I am somewhat aware of this Mic's brilliant reputation but everything has a shelf life. I want to know if this one is still worth the money . any comment will be greatly appreciated . Thanks :!: