Windscreen wiper... A mystery!

Salü municipality,

today I was kind of interested in taking care of my windshield wipers.
As is well known, the cones rot in their sockets. So why would my coach be spared?

After removal and disassembly of the mechanics, the right cone was only to be obtained with effort and puller from the socket. After everything was cleaned, greased and new O-rings were installed, the mechanics also ran considerably better. If not without some resistance, which is probably due to the riveted mechanics on the right joint.

After everything was brought back to basic setting and the test run looked promising, I reinstalled the whole rattle.

Now to the mystery:
Without wiper arms, everything goes perfectly. But as soon as the arms are mounted and I switch on interval, the wipers stop in the first third. ==References== They run on for a second and go back to the final position. The next passage runs through without a break.

I'm going through it on level one, but I can hear a very easy crack somewhere. Unfortunately, I can't always say whether it was before.

The behavior doesn't explain itself. Without wiper arms everything tutti, not with arms.

Any of you know that? Could the facial expressions have a overload protection?
I feel too tired about the first stage either way. She could be a little more brisk.

I guess I'd better open the gearbox from the engine and inspect the gear. It will probably be made of plastic and will probably be worn out.