SR5 Mech Vs Cash flow 126

Hey all,

Something that I have never come across before, but are you able to change mech from sr5 to a cash flow 126?

Basically I have an updated 126 and wanted to swap out the sr5 inside that only takes old pound coins. The problem is, the loom connects to the VEND BUS on the mpu5 board instead of MECH on the mpu5 board and the current loom doesn't connect to the 126. I have changed looms but get 'check software' error on start up... however, if I reconnect the plug back into VEND BUS but not in the mech I get 'coin mech missing'. Is there a way to switch? Or not?

Machine info: barcrest mpu5 Cock a doodle dough without note acceptor

Thanks