United-Carr M245 snap machine belts?

[Cumberland Highpower]

I'm going over a pair of United Carr M245 motorized snap setting machines.  Doing the usual, cleaning, adjusting, etc and thought to replace the drive belts.

My usual cheat method is to just remove a flat belt when I come to one and replace it with a heavy cogged v belt and changing the pulley on the motor to a V type while leaving the larger driven one flat.  This time around I may have hit a bump in the road.

Best I can tell, the driven pulley doesn't have any way around it for a standard belt.   I can't really get a good look in there, but best I can tell I'd have to disassemble the machines to get a v belt in?    

Anyone replace a belt in a M245 type before?     Any tricks or advice before I take everything apart?

They currently have flat belts w/lacing.