HP-41 modification: what is this (see photos)?

[Cococollector]

Though the hardware part seems to be solved, I post my further findings in this thread, not to open a new one:
I'm now sure, that commands having to do with X MEM lead to stop watch mode:

- ED: SW mode + 3-digit(!) difference display, sometimes alphanumerical, boxed star or other characters displayed (e. g. 00:00:00,0|D9*3, |=goose, *=boxed star). Registers always >600, which I deemed not possible.
- EMROOM: same as above, but with registers displayed (e. g. 00:00:00,0=D753)
- EMDIR: stop watch mode, no registers (00:00:00,00 ), leaving SW mode via SHIFT + <-, then X shows 1000 afterwards, no stack lift.
- CRFLAS: see EMDIR, X: 0,503
- CRFLD: see EMDIR, X: -0,513
- CLFL: see EMDIR: X: 0
- PURFL: see EMDIR, X: -1000
- SIZE?: see EMDIR: X: 0

Is there a connection between stop watch and extended memory (registers next to each other) and due to a maybe faulty RAM chip the content of one register gets swapped into one of the X MEM registers?
If not, that else could be the reason for this phenomenon?

Klaus