I work on a few of these units, most of the time is user error. If your screen locks up you'll need a power cycle. Putting grip tape on the runners will keep the cart wheel from spinning around and causing a jam. The alignment of the entry and exit doors is crucial,if they get too far out you'll need to adjust the pillow blocks on the main shaft that ties the doors together. Its very mechanically simple, if you look underneath you'll see everything is relatively basic mechanical parts. When the chain jams and takes up maximum carriage travel you'll have to unjam it, i usually remove the cart and run the t-bar out of the jam. Be careful,when they unjam there is a lot of force, makes a loud bang! Check the condition of the aluminum track and the safety arrestor, if they suffer a few nasty jams they can distort or burr the aluminum which will catch subsequent carts and increase your headache. And pflow does offer good support, call back again and ask for someone else!
