I hope its okay to post this here. MM3 modchip: https://www.ebay.com/itm/Multimode-3-MM3-PlayStation-1-PSX-PS1-PSone-Modchip-New-Prewired-/232495820131?hash=item3621d4ad63
I tested the same chip in a 1001 and 7501, due to the laser failing in the 1001 and the replacement laser only playing nice with original disks for whatever reason. The seller was extremely helpful, and provided support through swapping the modchip from the 1001 to a 7501. Prior to the laser failing, the chip was working great in the 1001, and it’s working great in the 7501 now.