Recently purchased my first vending machine; cb700 model 3151. Having an issue with my mag32sa bill validator, whenever it takes a $5 it spits it back out and continuously tries to eat another bill but when you stick one in it stops until you remove it and it continues to run until powering off and back on, in which case it goes back to normal (accepts ones, also the $5 acceptance switch is on). Any ideas on what might be wrong with it? It has a $5 sticker on the back of the validator, but I don't know for sure if it has been upgraded. Was looking into getting another bill acceptor that's already upgraded to accept $5's so that I can also get a card reader installed, are all magpro validators interchangeable?