One other thing I just thought of doing is to NOT attempt to remove the arms from the shafts. Since the main reason the arms need to be removed is to allow the cowl grill to be removed so you can do the real work, why not modify the cowl grill so it can be removed in sections? Take the screws out of the cowl at the firewall. The take a hacksaw, tin snips, sawzall, cutoff wheel, or what ever and carefully cut across tre cowl in 4 places. This would give you independently removable sections on the left side, right side, and center between the wipers, and a small section still remaining around each wiper shaft. Probably have to drill a few new holes to add a few more screws on the firewall to hold the cowl sections down. Might even be able to get away with just 2 cuts, each one inline with the wiper shafts. That would give you 3 sections total and the entire cowl could be removed, even around the shafts. Then, you could do just about any maintenance or repair you wanted to without having to remove the arms. Boy, I wish I had thought of this last year. I may have to do it to my truck anyway, hafta take a look tomorrow and see. If anybody's interested I'll do mine just for grins and take some pictures fer yall to see.
Eric