Installed new OT in my Bandmaster and now an issue with one channel

I installed an Allen transformer in my '67 Bandmaster head. Pretty much plug 'n play except for some chassis drilling for the mounting holes and putting in a switch so I could choose between 4 ohm or 8 ohm.
The only glitch was reversing the 6L6 leads. 5 seconds on, a loud screech, and shut down.. Resolved that issue..
Put it all together, plugged into the CRex, and it's glorious.
Channel 2 warms up as usual.
Channel 1 does not. The amp has to sit and idle for a minute or more and then Channel 1 comes in normally.
Not a tube issue. I have multiple sets of tubes and have changed/swapped all of them. (except for the power tubes). Same issue.

I did do the Robinette mod so that the vibrato works on both channels. But that was months ago and it's been fine.

Any ideas?

Quote:

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Originally Posted by Keethlawrence

...except for some chassis drilling for the mounting holes

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Start your troubleshooting there -- it's possible your drill bit nicked a wire on the underside of the motherboard or the vibration of the drill shook a solder joint loose. Failing that I'd opine that you have a wonky cathode-bypass or coupling cap somewhere in the normal channel.

Good thoughts. The holes were drilled pretty far from the board and there was continuous vacuum suction around the drill bit. So I don't think that is it.
But the vibration/solder joint thing is a very real possibility. Backed up by the fact that taking in and out of the cab a few times has completely cured it. Sure sign of a faulty connection.
I will just have to keep on eye on it.