Recently picked up our motorhome from dealership service center, one of the items I was trying to get fixed before warranty expired was the windshield wiper effectiveness that I previously identified. Attempted to fix this problem on 2 other occasions but attempts failed, this time I am happy to report success.
Problem was that wiper assembly lifted off of windshield surface on the last 1/3 of travel on the outward stroke at speeds, the faster one went the less effective the blade assembly became, this left drivers side rear view mirror useless in heavy rain, also limited clear vision of lane you were driving in.
Resolution was to replace the existing blade assembly with one that has holes in the blade support structure to allow air to pass through the assembly rather than lift the assembly off the windshield. Here is a photo of the new assembly:
note the holes in the replacement assembly, the OEM assembly was solid.
Replacement part number of the new wiper blade assembly is TV8-32, this is a Tru Vision Wiper Assembly part number, it works like a charm. Appears most RV Supply stores carry Tru Vision wiper assemblies.
Hope this is of help to others that may be plagued by this or a similar problem.