Kew Pressure Washer Repair Manual

I previously posted that I have a KEW Hobby pressure washer ...... been great to date ..that had started surging.
No shortage of incoming mains (pressure or flow rate) even tried different hoses & fittings to be 100% sure of that.
OK - as hose was crumbling away, .... bought a new hose, incl hose fitting .... so can now discount the hose, lance & nozzle from being the issue.
Loads of water through lance if trigger operated (motor off)When motor is on ... when lance operated it is surging ... aprox 2 sec full pressure 1 sec low pressure.
Now previously it was mentioned that when I release trigger .. pump still runs, and it uses a bypass valve to release the pressure .. and this could be at fault.
Anybody know what this would look like, and is this something worth stripping & perhaps cleaning.
Last option I suppose would be if there is somewhere that services KEW. Like many British Manufacturing companies - they are no more.

Kew Pressure Washer Dealers

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