Tektronix 2440 parts (knob, pwr switch cover) and advice needed

[bklein]

I bought a 2440 off Craigslist for $50 on a whim and got it home and saw the white phosphor cloud in center screen when I turned it on.  Took the case off to get ready to repair it and turned it on and the cloud changed to the display screen text and a trace eventually appeared.  Now, several months later, I tried it again and got the cloud but it heated up and got the screen text and then finally the trace image appeared and everything works. 
1. Is this a sign of bad caps?  I can pull and test them all if so.
2. I read that there is a memory chip inside that has built in battery backup that will eventually die.  Worth keeping this around if this is going to die eventually?
3. My scope has a missing Intensity knob (knob support base underneath is good), the power switch's clear cover has broken off.  I guess I can make something like it and glue it in but wondering if someone has a spare.  My scope is also missing the control panel cover (cap).    Interested in buying if really cheap.  I normally use a digital scope but may like to use this one for XY modulation visuals etc.

Barry

[EHT]

Regarding the old Tek parts there is a small online shop - QService, who stocks a lot of bits and bobs for Tek, HP etc. I used it recently and got stock in very good condition.