Hi, I know this is some years old at this point, but was curious if this was ever resolved, and if so, what the issue was? I'm going through something similar right now as well, just the left tension arm is the issue...
Any servo tension deck needs the opto referenced and then tension adjusted using a Tentelometer gauge as the book says. Lubrication of pivot rods will over time add to the problem but can be resolved if you recognize it. The 388 is far too large and it pushes technology too far which will with wear cause big problems. Putting 8 tracks on a 1/4 tape is asking for trouble. It may work when new but at this age look out. People have these must have a lot of time on their hands to figure out all the problems when they could have been making music using a more reliable 38 deck. These were nothing but a pain when I was at Teac and all the Technicians avoided it.
OH on those carbon trimmers- get rid of them and put Bourns Cermet trimmers on the board/ carbon are not reliable at this age. The substrate cracks and it will change day to day- Cermet from Mouser will be much better- that is what I do on other machines.
