Loss of vertical sweep in TUBE TV sets.

1. Be sure the TUBE TYPE set has a power transformer. If not DO NOT TRY THIS!

A quick & dirty trick I used to help troubleshoot tube type, PARALLEL WIRED FILAMENT TV sets with power transformers that had a vertical problem (After subbing the vert. output tube), was to feed the ungrounded side of the 6.3 volt filament into the grid of the vertical output tube. 
 If that stage was OK, and the set developed vertical sweep, then the problem was the drive to the vertical section. It was a fast check, and was pretty accurate too.

 It was really helpful doing home service with no scope. Most shops in my area did not have a scope for the home service tech, (or tube changer ) preferring to have the set brought into the shop for further troubleshooting.