Robbie, a pneumatic with a clogged bleed would play just fine, but it
would not repeat.  A clogged tube leading to the pouch could cause
sluggish performance.  Of course, a tracker bar pump in theory cleans
both the bleed and signal tube, so you gave good advice, but for the
wrong reason.

Offhand, if the rewind is getting sluggish, then the problem may also
include some of these: friction in sliding the transmission to rewind;
the rewind pneumatic and/or hose is leaking; the valve is not actuating
because of dirt on the upper seat prevents it from closing; and
finally, a pouch becoming leaky will eat up the signal and therefore
the valve is not lifted off the lower seat strongly enough.

Randolph Herr