Blade adjustment or setup help?

[mjd520 0]

My  Copam 4050 is setup perfect in SB and cuts correctly, however, I always do a test cut from the machine everytime I load material so I can adjust the downforce, and it cuts the vinyl perfect, and weeds out ok. If I cut a 3" x 5" sticker it cuts and weeds great, but if I cut 30 of the same stickers in one run, it is hit and miss with the cutter cutting all the way through the vinyl and I waste a lot of material. If I cut large letters, say 20", some letters will be fine, and some will not be cut all the way in the middle or other various ways(almost like it is scoring the vinyl).

I would appreciate any help or tips that I can get, as I am sure it is just some small adjustment I might be missing.

Thank you