HP test equipment has had problems with hardened lubricant on switch shafts.? The 8640B's bandswitch operates a cam that rotates in on two bushings.? When that lubricant hardens on those bushings, it's very difficult if not almost impossible to rotate that switch.? As you say, cleaning the old lubricant and using some light oil does the trick.
From: "K6OXN Bob" <bobk6oxn@...> To: "DRAKE-RADIO" <[email protected]> Sent: Sunday, February 4, 2024 8:31:01 PM Subject: [DRAKE-RADIO] RV-75 Function Switch
I have seen several reports that stored RV-75's have reported Function Switches that are frozen. In my purchase of a NIB RV-75 and having the Function Switch seized, I decided to look into it after replacing the switch with my spare. What I found was the shaft was frozen and you could not move it. After a complete disassembly I was able to carefully remove the switch shaft and found hardened grease on the shaft.? Cleaned with some alcohol and lubricated with fine machine oil. Reassembled the switch and it now works perfectly. The unit I bought had been stored since mid 80's so probably almost 40 years. I suspect whomever Drake was using as a supplier for switches did not know this. I think you might be able to soak the switch in some alcohol and that should loosen up the switch. Hope this might make it easier for those with stuck switches in the future.