[Test-Equipment] Question regarding HP-8640B

[Barry]

I recently purchased an HP-8640B and the bandswitch is very difficult to rotate.  Knowing there are delicate nylon gears inside, I opened the bottom and applied some extra twist at the Oldham coupler and managed to get the shaft to turn a bit more freely.  Also, the Peak Deviation switch will only move between the "5" and "10" positions.  Since these two mechanisms involve the same gears, I wanted to mention that.

Are there cleaning and/or lubrication points that will help free the machanisms?  After getting it to turn yesterday, after sitting overnight (in a rather cool environment), the bandswitch is again difficult to move so I'm figuring it is thickened lubrication somewhere.

Thanks for any help,

Barry - N4BUQ