A code 77 is related to the dryer air-flow flags not transitioning properly, so if you have a Thrust Pro, the follower likely isn't dropping for you.
Which model of machine do you have? If wall mounted, is it the older US2001 OHD model, or is it a Radius which also uses ultrasonics?
For trifoam, for either machine, those should be spraying out of separate manifolds on the left and right side. If only one side is spraying, you have an obstruction in the line somewhere. Clearcoat should be coming from the rinse halo above as well, but it doesn't have two distinct sides.
The arm would be used for presoak applications, and your high impact (or high pressure, depending on model), and possibly a rinse after trifoam.
If you can explain with more detail, I'll try to help. A serial number would also help.