I would assume that used machines are either destroyed by the manufacturer or resold only to licensed entities.
Machines were sold in Russia, and at the day the gambling codex contained only one chapter:
1. Gambling is banned
So, these casinos dumped machines as fast and as cheap as they can
when gambling just got banned nationally, you have very little incentive to maintain good relations with the manufacturer, and would rather just get whatever you can moneywise for such a large investment.