Ok so I’m taking my wiper arms of , and they looked like there held on with a grub screw which wouldn’t undo. So I attempted to drill it out after drilling out attempted to pull arm off the collar with the grub screw which has been drilled out, collar still on but arm off ??? So it appears nowt but the taper & splines where holding them on …surely not any input would be greatly appreciated as I’ll be putting em back on after respray

Oh sorry it’s a 95 N reg 300tdi

There is a splined boss which is held onto the winscreen washers drive spindle by a small grub screw against a flat (so it doesn't rotate and fall off.
The windscreen wiper arm fits onto this boss and there is a small spring clip that stops the arm falling off (the spline).
You clip the arm on, activate the wipers and then move it around to get the bottom and top of the stroke correct.

A small coating of grease will stop it rusting together...

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https://www.ebay.co.uk/itm/175334307413

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