Christian,
I absolutly agree with David s post.
Back in the ' '70 when I was maintaining 3 x HP 2116 B running 24/24 7/7 FOR
around 10 YEARS,
the ONLY memory related problem that I got was traced to a faulty transistor !!
( But I do not recall exactly, may be it was on a Driver Inhbit Card )
Anyway, from this only one case , not statisticaly signifiant ;-) the problem was a
Tx, not a C.I.
Wish you the same ...