mkIII 180

[lugnut526]

A shot time ago I picked up a mkIII 180 amp that looked pretty good . Tested the tubes ,all good. put new caps and bridge rectifier in for good measure. amp works good till it has been on for a while ,as in good and warm, then i doesn't want to key up. I can watch the relay with the cover off and it does move when keyed but not far enough to make contact. Is there anything I can do to fix it or should i send it out to get professional help. I'm not a tech by any means but I'm a good parts changer. Thanks in advance to a great bunch here on grumpys. lugnut526

[mark4]

I have seen these relays flake out when they get good and hot.
Someone had even beefed up the unit changing out the transformer/power supply. The extra heat caused the relay to act up when it was hot. He put a fan on the outside of the unit. And it resolved the issue. Also change out that 6BQ5 tube and see what happens when it's hot.

[lugnut526]

changed the 6bq5 with the same results