Thanks chaps for the kind words.
That replacement two way fuseholder arrived this morning, so I've fitted it and sorted out one or two other little issues.
I noticed that there was no stopper for the filling orifice for the high pressure water pump - no idea whether it had always been missing or if it's a recent loss, but I made another out of a bit of stainless bar - also no idea what the original design was but I'm sure that this will fit the bill.
I replaced the engine air filter, as I happened to have one in stock, and ordered up an oil filter. When it arrives I'll drain and flush the oil through with a new fill using the old filter, then replace filter and oil again - it only holds 1 litre so no great volume. I'll also drain and refill the high pressure water pump oil at the same time.
I've also at some time to replace the fine brass gauze that stops muck entering the diesel pick up pipe. There is a standard Jerry Can built into a holder in the main frame, and it has two 10mm brass pipes dipping in, that were originally protected by a wrapping of gauze soldered on forming a filter. Over the years the ends of the pipes have bashed their way through the gauze making it useless. I have a bit somewhere and when it turns up I'll effect a repair.
Meanwhile I gave it a good testing blasting away the moss that was growing on the ramp that leads up to my loading dock - it had got so bad that the forklift would sometimes slide down with locked wheels!
I burnt about 10 litres of diesel in 2 hours - I was 'steaming' rather than just using pressure really just to test the machine. Apparently it generates 390,000 BTU or 114 kW of heat