The PRT-MPF comes in two versions – the PRT-MPF-IB for the MPF-1B (7-segment display), and the PRT-MPF-IP for the MPF-1 Plus (VFD alphanumeric display).
The hardware for both variants is identical, except for the contents of the ROM, and the instruction manual. The schematics for the last hardware version (the Rev 6B, with ULN2003 driver) is in the PRT-MPF-IP manual
The capacitors on these boards degrade over time. If the MPF reboots when the printer starts printing, replace the two 100uF capacitors on the printer board. It may also be prudent to replace the two 33uF capacitors on the MPF-1P main board.
The paper used by the PRT-MPF is standard 57mm-wide thermal printer paper, commonly used on credit card terminals. This is usually available at low cost from stationers' and Amazon: https://www.amazon.co.uk/EPOSGEAR-Thermal-Credit-Card-Till/dp/B01DJH6R20/
Fred Jan Kraan has archived some of the MPF documentation and ROMs: https://electrickery.nl/comp/mpf1/doc/