Ooh, we're getting somewhere, albeit, nowhere particularly fast, but at least with that plunger unit removed I can have a think about what to do next. Had a spare 10mins after finally getting the 4x4 back together and noise-less yesterday, so had a closer look at the plunger set up. I had made up my mind to replace the springs anyway, as they had suffered a lot of heat in a bid to get the thing undone, but then in a fit of temper, I had attacked one of the shrouds - actually, it wasn't really a tantrum, but I thought if I could expose more of the spring, I could perhaps compress it and then get the mole grips or similar, on the rod which would give me a better grip than the broken screw slot. But it didn't work, because I couldn't get enough of the shroud out of the way. Anyway, that's not the problem. The problem is at the end where the rod screws into the frame. The Tractor Fixing Man pointed out that the thread isn't up to much inside the 'lug' on the frame, and I see now what he meant, but the odd thing is, the 'lug' on the other side of the frame, is larger - no wonder that plunger had already been removed, it probably just fell out! I haven't measured it in a very technical manner, just stuck the digi-measuring-thingy on it, and the left side is 13.7mm and the right side is 15.4mm. So have you got any suggestions as to how I can get the two lugs tapped and made to match the size and thread of the new rods that I'll need to buy?