Help with window wipers getting stuck

Hi all, need some help with some diagnostics. My window wipers are getting stuck about a quarter of the way up the windscreen and you can hear the motor still going. If I try to pull them up by hand they free up and will go for one cycle and then get stuck in the same place again, any help would be appreciated?

Check the linkage under the plastic cover under the bonnet, they wear out and jam up. You might need to get replacement linkage.

Have you taken the black plastic cover out from under the bonnet & been able to inspect the motor, rods & wheel / crank boxes?
That’s the first move; with this out of the way, you should be able to assess the mechanism. It is a while since I was in there but my initial reaction is the motor crank slipping on the motor shaft.
From memory (that’s a laugh) the motor shaft is about 10mm, then a ridged taper, down to an 8mm thread, nip up the nut on the shaft (13mm ?) & providing your problem lays there, it’s job done.
M