KidSquid was kind enough to mail me these pictures of U87 capsules. I think the capsules have seen some use and abuse...
"The pics of the mics are of a U-87, a U -87ai - these two have been
given to me for repair, when you see the pics, the U-87's top connector plug, has previously been through various states of repair. both the 87's , it seems, have got really dirty capsules, and the u87ai has got a scratch in the capsule ???, both mics make a cyclic wooshing sound. the 87ai is also getting high frequency distortion on peaks. i'm thinking maybe dirty capsules ?"
"The pics of the mics are of a U-87, a U -87ai - these two have been
given to me for repair, when you see the pics, the U-87's top connector plug, has previously been through various states of repair. both the 87's , it seems, have got really dirty capsules, and the u87ai has got a scratch in the capsule ???, both mics make a cyclic wooshing sound. the 87ai is also getting high frequency distortion on peaks. i'm thinking maybe dirty capsules ?"