TM36 fx loop problem- please help!

Hello, just joined to seek the advice of seasoned tubemeister players.

Long story short: everything was fine, then my TM36 head got knocked off a 1x12 cab, now I get intermittent drops in volume, unless I turn the fx loop off.

With the loop off I have no problems.

Before I pay a local company £78 per hour, does anyone know how to fix this or what is causing this?

Welcome to the forum. Sorry that your first post is something so serious.

There is nothing obvious I can suggest here. Such a strong whack to the amp could have caused almost anything. It could be something really simple such as a dislodged connector (unlikely with the connectors used inside), or it could be really serious like a cracked PCB. I would really suggest that you get it looked at by a tech unless you know your way around the insides of high voltage equipment. That's primarily for your own safety but also to prevent you making a bad situation much worse by simple ignorance of what to do and what not to do. There is a wealth of incorrect info out there!

You could try a factory reset of the software. There are more glitches caused by corrupt software than people realise and they can usually be sorted out by simply resetting to the factory state. If you do try that then make sure to back up any patches you use before you go ahead and reset it as these will be reset to default settings too. This is covered in the manual.