Firstly, there are some rolls out there where the perforations are just
too small; they do not play properly with problems as you describe.

Secondly, you need to test your valves effective bleed size. For this,
put the roll drive in neutral. Use a roll, preferably a test roll and
turn it by hand, uncovering the tracker holes slowly. Observe where the
note plays.

If you need to uncover more than 1/3 of the hole before the note plays,
your effective bleed is too much [or] leaking pouches or bleed cups too
big.

If you need to uncover less than 1/8 of the hole, your bleed is too
little [or] blocked bleeds or some mistake during assembly.

Let us know the result, please.

Regards,
Bernt Damm
Sydney