I have an oscilloscope that needs some retoration work within, the screen is very weak, have used a variac to bring up gradually but does not improve. Any suggestions as to where to begin restoring electronics?

:I have an oscilloscope that needs some retoration work within, the screen is very weak, have used a variac to bring up gradually but does not improve. Any suggestions as to where to begin restoring electronics?

It would help to have the make and model. Weak trace can be caused by many things: low B+, low high voltage, blanking or screen circuit problems, bad capacitors in these circuits, defective controls, and of course--a bad CRT.