hifi engine

Wanted: recommendation for an amp repairer in the UK

I have an early Alchemist Kraken ADP6 - the one with a crackle front plate for what it's worth - and there's an intermittent fault on one channel. If I press the PCB down the fault goes away. It's an on/off fault - when it's playing it sounds the same as the other channel.

I don't have a service manual and having re-sweated all of the soldered joints I have exhausted my skills. Can anyone suggest a repairer that could find and repair the fault? I live in Derby and work in London, but could post anywhere.