Our mid 2020 Plus Six has always had wiper blade judder on all three arms/blades since we purchased it with 500 miles on the clock. It has been back to the factory twice for wiper issues, the first time to try and reduce the judder and the second time due to the wiper mechanism starting to fall to bits behind the dash and also the wiper arm judder.
Logic indicates the two issues are related. Judder and wiper mechanism failure is due to a non-ideal interaction between the mechanism, the wiper blades and the windscreen. I had no such issues until I changed to the newer wiper blades. They juddered and put great strain on the Morgan wiper mechanisms I had been using for 30 years.
The Factory today is not fully aware that every (even minor) change entails what I call the Deadly Domino Effect (DDE) taught to me by Bill Beck, Service Manager (prior to Mark Baldwin) and then Development Chief (after Maurice Owen) for 25 years along with my own experience. George also helped. Change something small and simple and the Effects can be mind boggling and frustrating. In this case, the "better prettier" wiper blades create too much resistance/drag and that makes the older Morgan wiper motors and assemblies, used successfully from a time before we were born..vulnerable and obsolete.The new blades judder and along with the failing windscreen motor is an another example of the consequences of the DDE.
The easy fix is to go back to any one of the earlier blades (there are so many choices!) and forget it. However, you should be able to adjust the arms (which much testing and fiddling) so the pressure on the screen is lessened while still cleaning raindrops from it. That is something I am waiting for a have-nothing-to-do day to do. But first do as DaveW says. Carefully clean your windscreen and places.
As for RainX, I don't use it. What for? It is for cars without working wipers.
As for which way rain flows on a Morgan windscreen, I have standard windscreens of course. The rain flows upward when moving (wind) and downward when stationary (gravity).
COMMENT: Flat windscreens are infinitely fragile. They also pit quickly. Even the slightest curve would remedy the fragility. On the other hand, they can be replaced by any glass cutter with coffee table glass (laminated), though there are rules in the UK that spike the price without doing anything for quality.
I think they want to make sure someone wasn't so foolish as to use shatter glass. 🙁 Ex-UK I can replace the glass (and I do regular as I hate pitting) for 75$cdn. I use laminated glass, on the occasional whim, tinted.
In the UK windscreens cost me double. However, the good dealers merely swap the entire windscreen and frame..a few minutes work. 7 flathead screws. They keep spares.
Sadly, this is not the case for the long door generation. When Management decided on heated windscreens 1250£ (plus special packaging and transport) that ended the owners' holiday on windscreens with a thud.
gmg
P.S. If you go the fiddling route, use a digital scale under the wiper to see what pressure works for the rest of us.
