FYI, A lot of B/V's won't take $1.00 bills (singles) $5.00 is the smallest for many.
I respectfully disagree with this. Unless the validator has been set up by DIP switch or in the game software to not accept $1 bills, there's no reason why it wouldn't accept them.
Some validators are set up this way (I think New Jersey casinos are set up that way), but I think it's too broad of a statement to say that "a lot" of validators won't take $1 bills.
emelie, if the validator accepted $1 bills in the past, it will continue to do so.
When it rejects the bill, is it spitting it out immediately, or is there a delay while the bill is held in the validator for a second or two, then rejected?
I'd also try removing the cash can, re-seating the assembly, then re-installing the cash can to make sure everything is seated properly.