Well my TS830s isn't quite as badly damaged as I thought.It is now working OK on receive at least. Why is it now receiving? Well I am almost too embarrassed to admit this-but lets just say its important to make sure the fuse holder in the rig is screwed fully home!!
In any case switching on the heater switch shows that I have some plate current to the PA valves but the current rapidly increases within seconds and if the heaters were left on the fuse would simply blow again. The fault here seems to be similar to the one I had with my small SRW linear- that too showed a rapid increase in plate current. That fault turned out to be a combination of a blown capacitor in the finals stage along with a dying resistor. I hope to get some time over the weekend to open up the PA stage of the rig to have a close look.
I spent some time this evening trying to get the data lead I bought to work with my FT1000MP but to no avail. The DIN plug on the lead was indeed incorrectly wired according to the pinout data in the Yaesu manual. Two of the wires (earth and PTT) were going to the wrong pins. I resoldered these to the correct pins but I still cannot get the software to key the rigs PTT. I think I will stick to the TS450 for data-it works well in this mode and is simple to use. I feel a bit annoyed that I am left with a lead that doesn't do what it was bought for-but I guess it could be easily adapted to suit another rig. I have come to the conclusion that the 1000MP is not really suited to the data modes.