Hiya Gary, your post brought back memories of working with all the old detectors, manifoils and mersey’s. Haven’t got any company info for you but we used to send all our detectors and manifoils over to them (on the Isle of Wight), back in the 1980s, pre Euromark days.
Regards the work, I’m pretty sure they were always labelled and classed as ‘reconditioned’ but were always a superb job using the works jigs to knock out and replace all the pins and posts etc.
On Manifoils the main post for the wheelpack was knocked out and replaced, and all new wheels, new phosphor-bronze spacer washers, new circlips, new drop arm and bolt etc, same for the detectors they had all new pins, posts, lever packs and brass curtains.
This struck an extra chord with me because we actually considered tender for this very refurb contract when it came up for tender in the late 80s. Long story short is we didn’t, and eventually Euromark won it and took over for certain parts of the work.