Dark Picture
The only thing on the chassis is KTMF. The only thing I changed was the game board. I put the old board back in and it still plays dark. When I turn it on I can here static but no pic. I've checked all the connections.
Heres a picture of your chassis.
I know how you love monitors so you might want to send it out
for repair if you don't mine waiting a month or so..
if not we can try and fix it now.
If you have heater glow the voltage comes from the flyback.
Did you turn the screen pot clockwise to see a brighter raster?.
If OEM caps you should replace them see zanen electronics for kit
or if you have caps in stock then do a search for the cap kits and some
sites show the cap list and thier locations only around 20 caps for this chassis.
D605 is a good place to check for B+ band side of diode for voltage.
BP401 on bottom corner of chassis is the connector and very likely to get
bad connections on that plug pins so solder ity good.
If you have a tube checker you might check the tube also.