On Tue, 15 Dec 2020 08:54:36 +0000, The Natural Philosopher wrote:

So, mostly it is fine except that the timebase wanders randomly,
sometimes speeding up, sometimes slowing down. And it does this to
the
same degree in ALL timebase settings except the X-Y mode.

Is there a pot involved? Most scopes have a fine tune pot for s3eep
speed...if that is scratchy...

That would tend to produce step changes in the time base rather than,
as how I read the OP, smooth variation in the rate. Also implied by
looking at the timing capacitors, I've not known capacitors to step
randomly step change. Of course if the variations are step changes
then dirty/worn pot or switch or other connection is the likely
source.

--
Cheers
Dave.