MTH parts is down at this exact moment for me https://www.mthpartsandsales.com/
Changing a pickup roller is relatively easy- the screws most likely are external and do not even need to open the shell,
I would check for continuity on the steam engine between rollers using a meter.
Also suggest using contact cleaner like DeoxIT on the roller and rivet it rides on. Then use conductive light oil examples in this topic Edit- oops sorry, bad link.
https://ogrforum.ogaugerr.com/...l-for-pickup-rollers