It's not just the brackets that hold the glass to the regulator ... but that's a big factor.

It's not just the lubrication in the window tracks ... but that's another big factor.

Opening up the window tracks a little bit helps too.

Probably the biggest factor though is the little plastic guides on the regulator that keep the arm perpendicular to the vertical run.

Isuzu really screwed the pooch on our 'lectric windows design. Start searching the forum & read all you can on the subject. The more things that you try in combination, the better results you'll have.