ASW 24&27 rear fuselarge vents?

Hi all,
to day I checked, what I thought was the rear exhaust vent of the ASW24.
I tried, after removing the rudder, insert a thin wire past the tail wheel fender.
I could not get this thin flexible wire through.
I inserted a long vacuum hose from the cockpit side, to the very end of the tail
and hook up the blower side. The results were feeble indeed.
What have other ASW 24 or 27 owners done to improve this situation?
Regards
Udo