I used to know how to do this from using them more often....
You took off the cover, that's step 1.
Next I would turn off all the power and watch what the wheels do. Sometimes that is enough.
You just want to make sure you don't break the tape. You *can* fix a broken tape, but its easier if you don't have to.
When you power on, the arms pull the tape out and hold it against the heads. You have to figure out what's not happening and why (or why not), if its catching on anything, and then figure out what to do free the tape.
Does any of that really help?