Some things, sadly, can't be fixed on old stuff. I just spent hours carefully taking the Renault tractor electrical pod apart, layer by fiddly layer, in an attempt to repair the horn button, only to find that the contact spring-blade has rusted away to dust. I'll have to fit a modern button in a space under the indicators sw. Renault/Perkins only made about 450 of the three-cylinder P3, so getting a genuine replacement will be practically nil after 54 years. I've had better luck with the fuel pre-heater. Almost every part of this wierd assembly, [ the heater is buried up the air intake and you manually squirt diesel over a 12v 10A element with a little brass hand-pump, before hitting the starter lever ], has now been rebuilt with original parts, bar one 'o' ring, modern fuse capsules, a couple of 0.177" ball bearings and about a gallon of WD40!
