Sounds like a bent arm or a problem with the park on it. The bent arm could be the reason not all the blade hits the glass. If the arm is able to be pulled off and reinstalled at a different spline to allow for a full park, do that. May have been impacted with something at some time that bent the arm and damaged the park mode. May need to get a rear wiper transmission.
Here is the arm but no listing for rear transmission at RA:
https://www.rockauto.com/en/moreinfo.php?pk=1027956&cc=1380372&jsn=900
Turns out the rear transmission is part of the rear wiper motor:
https://www.rockauto.com/en/moreinfo.php?pk=338717&cc=1381047&jsn=866
Welcome to the forum and post some pics of your rig, inside and out.
We recommend that you put all your rig(s) info in your signature so we all don’t have to guess at year, make, model, engine size, trans, rear axle locker…….etc. While you may have posted pertinent info in your first post, you may forget to do it again and the info is needed by us anyway. Makes it way easier on all members that attempt to help, to have that info right up front. It is also recommended that you take a pic of your RPO codes, on the inside cover of the glove box, and post that image in your signature. All this info will greatly help those that will try to help with a problem.
If there is any other info, like upgrades, mods or recent mechanical/maintenance work done, that would be helpful in any post as well. Too many times a question is asked by the poster and after about 10 responses we find out that the poster has done recent work to attempt to fix the problem or work that was done that SEEMS not related to the problem.