jgcycle

My tip of the day:

My refurb of a vintage bike with 105 group had those crank dust caps made of plastic with 2 holes in them. Since I'm a newbie, I thought I could pry them off. Ha! They're threaded and I totally destroyed the cap with plastic threads still in the crank.

Other side: Found a 3/4" heavy duty staple (like you pound into the basement when running heavy wire), squeezed the prongs together a little tighter, pushed way into the holes and used some pliers to unscrew like a charm!

Crescent Cycle

I'm surprised they were that hard to remove. They must have been corroded in place. I have some 1st generation 105 cranks, and I just used an inner tube to undo them. No chance of making the holes look ugly or scratching up the cap, especially when you have those Campy chrome covers.

spinbackle

I used to have those pedals, still do somewhere filed away. I had good luck with the tips of needle-nosed pliers (before seeing the need to invest in some pin spanners). I used those needle-nosed pliers quite a few times on crank dust caps come to think of it (Shimano Deore XT cranks come to mind).

Andrew R Stewart 

It shouldn't be too diffecult to pick out the remaining plastic, stuck in the threading, from the crank arm. Dental picks, spokes sharpened and bent or tiny slotted screw drivers do well for me with this job. After the remains are gone thread in an extractor to act as a thread chaser. If caps are replaced lube the threads first. Sometimes removing the arm retaining bolt/nut helps to get better access, sometimes it won't come out without the clean up first. Good luck. Andy.

Wanderer

Lock ring pliers work great................

cny-bikeman

Yes, there are multiple ways to remove those dust caps, destructive and otherwise. A little heating with a blow dryer or similar makes the task easier.

HillRider

+1 Prying them off with a screwdriver falls in the "destructive" camp.