Worth noting the above here for posterity and the DLP page that described the checkpoints in PAYG as discovered by @DirtBagXon .
https://www.dragons-lair-project.com/tech/enhancements/dle2xsequence.asp
Pay As You Go interruption point When the PAYG option for 2 interruptions per game is enabled, this is the 1st point at which coin(s) are required to continue play.