Main earth connection off the battery to be put on there, under the fuel tank, to minimise water damage/corrosion. Anyone with an opinion on where's best ?
What I have helped owners of these old machines over many years is starting problems.
The starter relies on a good electrical contact with the engine block to be able to flow current. On older machines, these mating surfaces get corroded and now the electrical ground path becomes iffy.
My advice has been to add an additional ground cable with two eyes, one on each end to their tractor.
Chose any location you wish for the main battery cable ground but then run this two eye cable from that point to a starter mounting bolt.
Your main harness ground point could be either the main ground cable to the block or the starter mounting bolt.
Dave