[Test-Equipment] need help with Fluke 8840A/AF

[Eugene Hertz]

Hello all, 

A few months ago I purchased an 8840A/AF on ebay. The unit arrived and many of the buttons did not register not matter how hard I tried to push them. I sent the unit back and the seller said he was able to clean the contacts of the unit. When I received it the buttons were working except 4-wire resistance. That was ok, since that is a mode I didnt anticipate needing much. However, now just a few months since then, several buttons are again not working, most importantly the 2-wire resistance.

So, I wonder if in fact, the contacts need cleaning.  My experience with dirty contacts is that they sometimes work sometimes dont. And usually if you mash the button or press it a few dozen times you can get it to work. In this case, nothing will make it work. I will add that I have used this meter maybe 5 hours total since I received it with buttons working. I may have only pressed the buttons a dozen times in that time, so it has not been abused.  I am puzzled why the buttons in so little span of time and with so little use might have gotten "dirty".

My question to the group is: 
a) Is this a common problem with these meters?
b) Is this an easy fix (for a novice like me)
c) Any one have a working one they would trade plus cash?

Thanks!
Eugene