Pixie - do you know for a fact that the pedals are the same that you use in spin class? Have you checked for sole interference? Are you positive the recommended cleats are the same for both pedals?
It depends on the cleat whether old/new makes it easier to clip in/out.
Get your shoes into the pedal somehow, remove your foot and then turn the pedal over and look for interference from the sole. If this is the case, there are spacers avaialable or you can get out the old Dremel tool and do a little remodeling of the lugs.
Frends know gud humors when dey is hear it. ~ Da Crockydiles of ZZE.