u87 pattern switch

my old u87 has problems with the pattern select switch. The signal craps out, then when I move the switch to another position back and forth a couple times the signal is there again. But after a short period of time it goes silent again.

Does anyone have experience in cleaning the switch? It does not seem trivial to get access in there.

On another note: is it possible to rewire the electronics to have the mic in cardioid only? I really have enough other mics to use in omni or fig-8 and almost exclusively use the u87 in cardioid pattern.

Thanks for any thoughts on this...
Marten

Yes it can be done , but you have to be very carfull ,  the contact are problably oxydised a bit  and create such of a problem wich is a classic problem  by the way ,  if you look at the schemo the cardiod mode is actually on where the switch does nothing in the middle position if the signal is still intermittent there then you will have no choice of going in there and hardwire the connection that is missing , or there is a loose connection wich has nothing to do with the actuall switch ,


Hope this ,
helps,
Dany,