UPDATE:
Followed all their instructions, and the screen still clogs...BUT...it's not as bad as it used to be, so the screen doesn't "blow off" like it used too. The vacuum seems to work fine like this since there are auxiliary vents in the discharge tube on the shredder.
Vacuumed up about 2 acres of long grass, and after running multiple loads through it, everything seemed to be working fine even though the screen was clogged.