Sick Croft preamp

[Stranraer]

Sorry for a VERY general question. Fired up the hifi last night and got a loud, constant buzz through one speaker. Volume control doesn't alter the level. I'm pretty hopeless technically but done some checks and narrowed it down to the preamp channel, not a cable or amps.
Before I take the lid off, could anyone take a guess whether this could simply be a blown valve which I would be able to swap out myself ?
Anything other than that and I'm stuck.

[Macca]

It could be a blown valve, but it could be something else. First step swap valves around see if the buzz changes channel.

[walpurgis]

I'd start by waggling the valves in their seats, to make sure the pins are in proper contact.

[Jimbo]

Check the fuse in the back of the preamp.

[Lawrence001]

Check the fuse in the back of the preamp.Would that affect one channel though?

[Bencat]

I am going to see Glenn Croft tomorrow for him to revalve and upgrade my Croft OTL 3 power amp . He is back doing things in the workshop so if you send him an e-mail he may be able to help .

[Stranraer]

Thanks all, I'll follow your ideas at the weekend and report back.
If all else fails, I'll email Glenn as suggested. Not a bad part of the world to visit if I have to drop it back.

[Bencat]

Took my Croft OTL yesterday and Glenn was his usual taciturn self . he is currently very busy and I was quite surprised that he had three other OTL amps along with mine that all needed some form of fixing. I will have to be patient and wait as I think it will be a few weeks before Glenn has time for my amp . I can say having had the amp serviced by Glenn recently that his work is top class and the price was in my view very competitive I could even push that to being very low. If your Croft needs some attention I would advise getting in touch no better person to get things sorted and working correctly than the man who designed and made it originally .

[donmarrese]

Totally agree with Bencat, just chuck it in a box and send it to him.

Sent from my ONEPLUS A6013 using Tapatalk

[Macca]

But if it's just a duff valve that would be a waste of time, money and effort. Plus if he's busy it may take weeks before you get it back and you're no better off if there was no fault to fix.