I'm not familiar with the 2215, but have delved into a 2445B and 2465.
Most Tek scopes have fans, and if they aren't working properly then components can overheat and fail. That's certainly the case with 24x5s, where if you are running it with the case off you have to blow cold air across the board.
It looks like the CRT HV (3kV) and EHT (17kV) voltages are roughly OK.
Check all the internal PSU rails for their voltage and lack of ripple. (Fine tuning can wait until later). If anything is grossly amis, fix that first.
Then start looking at the voltages on the CRT vertical plate connections. The two plates will have voltages around X+Y volts and X-Y volts relative to the chassis, where X is I guess ~45V and Y is up to~20V. When the beam is central Y=0. That means the differential across the two plates would be 2Y.
My guess is that there is no voltage on the top plate, and you'll have to find out why. It might just be the connection has fallen off. But if it worked properly for a while and the fan isn't working, then the Y plate driver might have failed.
The Yahoo! TekScopes group has a wealth of information and knowledge.