PTFE is slippery stuff, aluminium foil would be better to grip the spindle, new arms better still. If the arms have bottomed out on the spindle, washers won’t help.
Thanks to all, some great suggestions. Will try to get some rain x delivered to the site as back up. Will work through the other suggestions when I get to Denia tomorrow as it’s too hot here ( 29 degrees) to do anything else
Because I had fitted an intermittent wipe relay which takes over switching all wiper motor power from the worn out switch, boosting the torque, so the wipers will now move on a dry windscreen ... I just had one of my new wiper arms lose its grip on the spindle. Looked at the splines, looked bad from a distance, maybe a clue in the closeup.. different metal colour between stainless steel and zinc-ish stuff. I thought..its knackered, nothing to lose, lets try cleaning it up with a needle nosed file. Poked tip of file onto splines and soft metal flaked off worn from the wiper arm casting. Literally a minute later... Bolted arm back on, grips again..
