Tektronix 2465 - Microprocessor's fault?

[Initial_Chris]

Hi everyone, this is my first time writing on this forum.
A friend of mine gave me a Tektronix 2465 Oscilloscope that he had kept in his basement for years.
I tried to turn it on but obviously the RIFA capacitors turned into a stink bomb.
I changed all the RIFA capacitors (even the still healthy ones) and tried to turn it on again.
When it was first turned on again it showed a narrow trace which could be controlled in height and brightness, but the oscilloscope showed no signs of life and the LEDs remained fully lit,

I tried to turn it back on and from that moment the LEDs all light up for 1 second and then turn off. No trace is shown (other than some random noise for a few fractions of a second).
No controls respond, not even the beam finder. The fan spins correctly.

I checked the power supply voltages and they are all within range, including ripple. The only wrong voltage was +87V (which makes me worry that the U800 may have burned out), as it read +93V. I solved it by replacing U1281, Q1222, Q1223, Q1221.
Unfortunately, even after fixing all the voltages, the oscilloscope still does not boot.

Could it be the fault of the wrong +87V that has burned something that allows the oscilloscope to boot?

Sorry for my English 

Edit 1: I tried moving the jumper to "DIAG" and measured the entire address bus.
All signals are "clean" square waves except D10 (Pin 19) which has a very high falling time.
With the jumper in the normal position, while all pins are outputting data, D10 appears to float around 5V.
I'm guessing it's the microprocessor's fault at this point. Can I replace it with any MC6802P?

[Swake]

Have no experience with repairing this scope, but I would say yes to your question about it being possible to swap the CPU as it does not have any ROM and therefor is not programmed. Just make sure to replace with one running at the same frequency.

That said, from your scope picture the pin is at 4V not 5V. That indeed does not sound correct.
You named it D10, but it is A10, that is an address line.
The CPU might be the issue, but also any other chip interfaced on that line.
If the CPU is socketed, and thus easy to remove, you could try measuring the address lines with a multimeter in diode mode and resistance mode. Check for similar values between the address line and GND, Vcc and other address lines. If A10 is substantially different you have a good indicator.