I've serviced Shimano pedals (the older SPD-R models). Do not try to undo the plastic collar with anything except the TL-PD40 tool - it is very easy to damage the plastic. The tool makes the job easy. Note that the collar on the right side pedal is left hand threaded.

Once you're in, follow cascade 168's excellent directions. It would be worth having some fresh grease and spare bearing balls on hand, I believe the correct size is 3/32" - it was for mine. You might as well do a full service once you get them apart - they are worth it. My SPD-R pedals have given excellent service, in the last five years I overhauled them twice and they are still almost as smooth as new.

Good luck,

Ed