Vendo 821 double vending

[Kens Vending]

I have a vendo 821 that is double vending 20oz bottles in column #9. I have the depth set correctly (2). It doesn’t do it every time but maybe one out of four times it will vent twice. it seems like sometimes it doesn’t recognize that the rear bottle has vended because it hits the shoot so lightly.  You can’t adjust the shoot sensor sensitivity can you?
 

Thanks in advance!

Ken

[AZVendor]

Dsvendinginc.com/images/PDF-manuals/v24.pdf

[tismael56]

Hey Ken, several pictures of your setup would help. You can add to your gallery and post a link here or open a photo sharing account on another site and link here. I am thinking that it may be the gauge bar/ your cam settings (I believe the 721 and 821 are similar). 

[Vendo Mike]

I often see this issue when the delivery chute has been removed and incorrectly reinstalled.  There are "ears" on the rear of the chute when are meant to go into slots in the rear wall of the machine.  When the "ears" aren't in the rear slots, the chute will sit up too high at the rear causing soft drops or jams.  When installed properly and the front mounting bolts are tightened down, the chute gets a slight bow. This tension is what the vend sensors mounted to the bottom of the chute are calibrated to.  They should sense when a beverage lands on it even with "soft drops".  

Are there any errors? VS1 or VS2 would be Vend Sensor errors if either of those have failed. 

The V21 series doesn't have a gauge bar to set. That stopped with VMAX (548,720, 840) The only mechanical setting is the product slide also known as the "can clip" on the bottom right of each column and the rear spacer.  Ensure the rear spacer is set correctly.  Should be no more than 1/4-1/2" of space between the rear drink and the rear spacer to help prevent bridging.  The product slide should be set completely forward for cans (packages shorter than 7" tall) or back for bottles (packages 7" or more in height)