AMS Sensit 3 giving extra product

[Gretsching]

Hey guys, I'm new to this site but I've been lurking for quite a while. I apologize if there is already a section that this question can be answered in, but I'm still not sure how to navigate 100%. 

    Anyway, I have 2 AMS Sensit 3 visi combos on the road that have identical problems. Occasionally when I test these machines with money, and buy a product, the machine will act as though nothing was vended, thus giving the customer the opportunity to "make another selection" even though they already received the product they previously purchased. After the second selection is made, and the customer gets 2 products for the price of 1, it goes back to normal. 

     I never noticed any rhyme or reason to this problem, and it has happened with candy rows and beverage rows. Now I have been to these 2 machines and tested both with money at least 20 times consecutively without any free products being given... then there are other times when I test them and it happens 2 or 3 times out of 10. Any ideas on what I can check or test to resolve this issue? I also should note that it most likely isn't happening an obscene amount of times as I never walk into a machine that's empty with very little money inside. But, nonetheless, it is definitely happening because the owner of the one location told me an employee said he was getting 2 snickers for the price of 1. Any input or advice would be greatly appreciated, thanks!

[Chard]

I've never had many problems with AMS drop sensors. If you have an actual ams sensit 3 I believe it has the option to set the motors to home or drop sensor settings. If it is a sensit  2  or 1 that has been upgraded to a sensit  3 you do not have the option of setting it to a home setting on the motors .  In either case, if your drops are set to a drop setting, as I believe they are from the factory, it will frequently drop two items instead of one as the drop sensor is not triggered until a product passes the sensor.

If what you're describing is indeed  a malfunction of  the vending machine and because your problem is intermittent I would look for lose connections or broken wires between the drop sensor or the board.   If that doesn't pan out you could consider either a board replacement or replacement of the drop sensors. 

I hope this helps.