I'm trying to remove the wiper cowl grille so I can run wire thru the firewall. So I unscrewed all the screws holding down the grille, and removed the nuts holding the wiper blades on. But the wiper blades will not pull off the bolt. Do I need to do something else or just use more muscle? I was worried somehow messing up my perfectly working wiper motor. TIA.

I had trouble with that and I used 2 different ways to get them off. For the passenger side, I was able to do it by lifting wiper blade at the hinge -like when you clean your windshield- and them pulling the arm straight off the bolt.

For the driver's side I used a battery terminal puller to get it off.

Oh yeah, I also used some PB blaster (like liquid wrench) to losen everything up.

Just 'bump' the wiper arm 'hub' near the spindle, its a taper seat..us a rubber mallet...'with care'.!

Or after you unbolt the wiper arm,let it snap back down on the windshield a few times.Or fold the arm up and push down on the arm.Just use some of those big muscles!

When you put it back together, use a little anti-sieze compound on the splines so that it will be easier to remove if you ever need to again.