Airflorida, these are your words...
There is a lot of problems that could be fixed by the aircraft owners in the field providing they have qualified technicians who have tools and service manuals. But the FAA does not allow this and the owners have to send avionics instruments with the minor problems to the shops.
You (and your friend) have neither manuals, training, knowledge nor legal approval. I'll put this simply:
YOU ARE NOT ALLOWED TO REPAIR AN AIRCRAFT'S FLIGHT INSTRUMENTS BECAUSE YOU ARE NOT A LICENCED ENGINEER
So do us a favour. Go to an approved facility and get them to install new or reconditioned instruments. But make sure that you tell them you took the old ones out by yourself so that they can check the lines for damage, debris, tools, bad joints and seals etc. which will undoubtably be there. Failure to do this will invalidate any work they do, the certificate of airworthiness, the aircraft's insurance and I dare say jeopardise the owner's airman's flight licence.
You are a silly person trying to commit a criminal act to save a few bucks.
PM