Can anyone recommend a repairer for Musical Fidelity amp?

[sunbeam alpine]

I have a Musical Fidelity A1 amplifier dating from the late '80's. It's paired with a Linn Sondek and a reasonably decent CD player, driving Mission speakers.

It does eveything I want perfectly, but recently the volume knob has become very crackly (when I rotate it to increase/decrease volume) and one channel is noticeably quieter than the other. The quieter channel does occasionally come up to the same level as the stronger channel, but this doesn't last very long.

I've already swapped speaker outputs and audio inputs, so can confirm it's the amp which is at fault.

Does anyone have any suggestions either that I can try myself, or recommend an address (preferably in southern England) who can repair it?

I'm in Belgium but in the UK at least once a month.

Thanks in advance!