Robbie,
Once adjusted would it be possible to finally lock them by drilling through and using a small SS self tapping screw?
Peter
I have these adjustable length arms on my Morgan, I thought they were standard. I've not experienced any issues with them changing length. You could probably do an invisible fix if they did move by poking a lump of Sugru up inside the wiper arm to hold everything in place once they had been set to the correct length.
