Where There's A Will...
... there's always a way.
To check for leaks and wildlife, an inspection with the shuftiscope and a good shake was followed by a couple of litres of diesel left overnight in the tank.
With no signs of weeping around the seams and no puddles on the bench, a good thick coat of lorry chassis paint was applied. The problem remained that the original sender unit was kaput, and I wasn't too sure about the gauge either. I sent off for a new sender unit that had matching mounting holes and hoped for the best. On its arrival and setting up the system with my new 12v power supply, moving the sender arm to the full position, the needle moved from the 'E' no more than 1/16". Hmm, same pickle I was having with the old water temperature gauge and its new probe.
Rummaging about in the stores, I found a Ford fuel gauge dating from the 70's. Hooked up to the new sender, it worked perfectly. I was going to have to put the innards of the Ford gauge into the Jaeger body. In so doing, a couple of issues would need to be overcome: the Ford mechanism worked in reverse to the Jaeger instrument and the needle swung from the bottom of the gauge instead of the top.
I hatched a cunning plan. The Ford's face was rivetted on to the mechanism, so it was a tricky operation to grind the heads off...
... and for once I managed not to break anything.
The Jaeger box was then drilled to accommodate the Ford pins. The pins had also to be insulated from the box, so I used the heat-shrink tube on the studs trick again.
It was a bit of a squeeze, but there was just enough room, and the needle didn't have to be modified - other than a lick of black applied with a marker pen.
Now that the gauge worked in reverse, all I had to do was remove the lower segment of the 'E' and add it to the 'F', then file down the stop pins to allow for the slightly greater arc of the Ford needle.
The casual observer wouldn't notice the change...
... and it was a relief to get the delicate instrument back together again.
I was than able to complete the installation of the new sender and the fuel pipe. I'm going to have to think carefully about routing the line as I must cross the chassis at some point...
... to meet up with the line that I've started to install at the other end. I'm sure I can work something out.