Thank you, yes it helps but I have 153mm from centre of float to centre of spindle. Looking at the float there has been a lot of soldering in the past - can you confirm that the float should be at right angles to the wire, as in a paint roller, or longways?

L shaped.

I'd use the measurements as a guide but then make sure that when the connected gauge reads less than a 1/4 tank or 1 gallon the float is just sitting 1/2" above the bottom of the tank. Measure down into the tank to the bottom and set that distance between the sender flange and bottom of the float. It's hard to get this and the 'full' readings both reading correctly but of course it's empty that's the more vital information? You can bend the wand a little to get the float position at the right height at the two kinks descibed above.

Dave

Thank you for that advice. I now have everything re assembled and fitted and not working! So, I see there is and article on Cornwalls website on checking through the system so now have that in front of me on the bench.

Just to update this thread - I have the system up and running but the reading on the gauge is variable and no where near correct and won't record anything over 1/4 full, so I have come to the conclusion I probably need a new sender. I suspect serviceable ones are tricky to find but I remember reading somewhere that a mini one could be adapted.