Have a good sniff of the fuse box any smell of burning?? If you've got to replace it make sure it's the correct one for the year and fuel type.
It's interesting that you say that because before the fuse blew & the pump knackered itself we did smell something odd but we were driving through a little country village and attributed the smell to that.
Don't leave it running more than a 10 seconds at a time as you may blow the thermal trip
the reason i say check your other relays and board is that if you see any damage then it solves a lot of other problems happening later. Have you checked the plug the compressor plugs into on the loom?
If those wires have been damaged or the pins are corroded they can also cause an issue
The wonderous world of P38s
But we do love them Kurt............................................

The new compressor has arrived and it's not in the car yet but it does pass all bench tests, as it should. However, we have found what we believe is the problem. It is at the fuse panel. We removed all of the plugs one at a time underneath it and didn't find anything odd until we got to the blue one. On the blue plug itself, we found what looks like slight burning on one of the pins and its socket (Apologies if that isn't the correct term. I forgot to take a picture of that but there is no evidence of burning on the actual tab). Upon removing the yellow one next to it we found a big issue. The plug was caked with corrosion. In one area it was at least 1mm thick. We then removed every relay & fuse and checked the top of the panel and there was no evidence at all of corrosion there. That isn't to say there's not any in areas we couldn't see. I think I may actually take each relay out and test they are all working properly too.
Here are some pics. I hope you can all see them.
Oh, the left rear bag is leaking. Well actually I don't know if it is actually the bag but the left rear dropped overnight (happy days!

). I never noticed it before because I didn't know about removing the EAS relay (I've forgotten its proper name) under the left front seat and how removing that stops the car from automatically lowering to access mode plus, I also always lower the car right down after driving it to make it easier for me to get in & out of it(I have a few physical health issues so my wife is the spanner monkey for a lot of the stuff I just can't do). There are definitely no air leaks at the valve block. Last night I used a very liberal amount of soapy (a lot of soap) water to check all around the valves and at the grommets where the airlines exit the block. There are also no leaks at the EAS bypass I have installed. So I'll need to put the car on stands and have a look underneath to see if I can find where the leak is because it, as far as I know, can only be there.
Ok, so what am I going to do next. First I will be installing the compressor but I won't connect it to the wiring of the car. I just want it in there out of the way so it doesn't get knocked over and damaged somehow. Then I guess I'll have to tackle the yellow plug on the fuse box (why do I keep saying panel?

) pull it apart and clean it up, or more to the point whatever you guys advise me to do with it. I need to get up to the automotive experts at Halfords (they're professionals

[to be fair one of the lads up there is very knowledgeable]) to get the negative battery terminal changed. The positive terminal is in virtually new condition without any signs of wear & tear.
Anyway, onwards we roll. Thanks again guys.
Regards
Craig