How much friction is acceptable in the wiper rack when it runs in the tube?
Is the curved section of tube from the motor to the first wheelbox able to be removed/ replaced? Any tips/ tricks
The tube is listed as a part, eg replaceable with part numbers for LHD or RHD. If there is a kink in the drive cable it may bind up.
It should slide out with a little resistance, as you would expect it being grease filled. Hard to say. Inspect cable, check for wear.