I got a pair of DX's today with the original endcaps in them.
Needed to remove them so i could replae the bearings.
I tried to get some knackered ones out from another set and they just crumbled, as the plastic had jsut gone hard and cracked.
My tip .. warm the pedals up with a blow torch, just to warm the plastic end caps up to make them more supple.
You can then carefully prise them out. :-)