c4 adjustment

Had a leaking vacuum mod in c4, replaced with correct mod but now slips 1st-2nd, should I adjust mod or band? Had no slip problem until change.

 

Adjust the modulator....Make sure the small rod is still inserted in it.. I know a few people who lost them while chaging the mod and didn't even know it...Trans shifts all over the place without it...

 

Make sure the vacuum is good at the modulator. If so, pull the hose off the modulator and insert a small flat blade screwdriver. Turn clockwise 1/2 turn and replace hose. Drive car and check shifts, if still soft, then repeat the adjustment, but do not go more than 1 1/2 turns total. If still soft after adjustment, then a band adjustment may be needed.