US5 Loading Material - Load Cycle not long enough

[mrender 1]

I am finding that the load material cycle is not long enough to purge old material out of the core.  I am pushing filament into the feeder until it just grabs (about flush with the top of the feeder).  Obvious thing to try might be to poke a bit more filament through but this usually leads to the filament bumping into the core and the feed gear ripping a lump out of the filament and stalling.  I am only able to get around the problem by manually pushing filament through to purge.  Of course with the material and feeder situated around the back of the machine (genius) this is all a bit of a pain, is there a way to extend the load cycle?