RCA chippercheck problems
 

I know chippercheck was really designed for the CTC185 and up, but
thought with my nice homemade testclip to clamp over the CTC175-187
eprom, it would be a good thing to always download the eprom to a
computer just in case of a future eprom failure on the customers set,
I'd have the file, take a couple minutes to reload the chip. Now the
problem I have is about 1 in 10 sets, the *good* eprom is ruined when I
hook the chippercheck to it, I get a "communication not established"
note, and the eprom is officially dead and needs replaced to revive the
set. This has happened now 3 times in the last month on good working
sets. I'm extremely careful while attaching the clip to the chip,
hooking the 5v and chippercheck up to ensure no static is present, even
ran all the leads 12" away from the CRT of the monoitor in case that
was somehow causing problems. Now I always copy on paper all 75-80
eprom settings before hooking up chippercheck, but this is annoying.
Anyone else see this or have any idea? I guess maybe I should leave
this chassis be and not download the eprom? No problems with the
185-197-203, just these older chassis that don't have the service plug.
Ron