External UltraNav keyboard repair

[aluke]

I am a long time user of the old SK-8835 keyboards with the UltraNav plus numeric keypad
I have replaced the main keyboard portion several times by cannabalizing more readily available SK-8845 keyboard from ebay, but now I have run into a problem with the numeric keypad on the side going bad.
Does anyone know where to source a replacement for the numeric keypad for the SK-8835?

[crashnburn]

I am a long time user of the old SK-8835 keyboards with the UltraNav plus numeric keypad
I have replaced the main keyboard portion several times by cannabalizing more readily available SK-8845 keyboard from ebay, but now I have run into a problem with the numeric keypad on the side going bad.
Does anyone know where to source a replacement for the numeric keypad for the SK-8835?

Can I get some advise?

Did you used to just replace that verbatim? Or Did you also follow some kind of MOD?

Also what kind of cleaning/ maintenance did you do, if any to keep things going for long?