Improving wipers

[Juular]

I know the 240 is known for having sluggish wipers, but something really isn't quite right with mine.

Normal speed is just about alright, but I still feel it lacks power, and if the screen isn't actually saturated with rain the wipers judder and jump quite badly. This is with both a brand new windscreen and new wiper blades by the way.

The other problem is that setting them to high speed doesn't actually speed them up at all, they run at the normal speed.

The motor itself I have completely stripped and rebuilt with new brushes and shaft bearing, repacking it with grease. On the bench the motor is quiet, powerful and quick. When I feed voltage to the high speed pin the motor runs about twice as fast. I think I can eliminate the motor.

Without the motor attached I can move the wiper mechanism under the dash by hand without any resistance at all, so it's not seized or binding.

What's left.. the wiring from the column switch works correctly, tested with a multimeter showing that high speed setting supplies the high speed pin as it should.

I've beefed up the earth on the motor by running a thick cable from the case straight to the battery negative.

The only thing left is to check is the relay and any grounds that supply the motor feed. Does anyone know what and where to check on this front? Would a failing relay cause slow wipers? Where actually IS the relay?

It could be that although the motor is getting the right feed, there's resistance somewhere along the way?