For anyone who may be intrested.... Have a similar problem.

After days, of Playing with my front wipers trying to cure a grinding noise, i bit the bullet and fitted a new motor.
This cured the grind/graunch... but left me with a knocking noise at the start of every oscillation.
so it went, Knock-knock-wipe....Knock-knock-wipe....Knock-knock-wipe and so on.

Pretty confident the new linkage (3 month old) wasnt at fault, i then fitted 3 new rubber mounts and captives.
This didnt cure it.
I then, stripped the new linkage down to see if there was any wear on the spindles out of curiosity. There was not, it was perfect... no corrosion/ no wear.. I then greased up the linkage as good measure and refitted.

Next step was to renew the 2 link rods..again this didnt cure anything.

So, back to the linkage...
The spindle ends are pressed into the main linkage bar, and crimped to secure!!!!.
Turns out one of mine had worked loose, and with some pressure (wiper starting cycle,) they move.



This will be returned under warrrenty on Monday hopefully.

So in the meantime, ive refitted the old one.

Maybe this could help someone else on here one day.