The Dynapar Cat list the F10 as a commutating encoder?
http://www.dynapar.com/uploadedFiles...derCatcmf2.pdf page 2-66.
Did you swap the encoder or the complete motor? As if it is a commuting encoder you would have had to re-align it when replacing.
It looks like you have a 500 pulse encoder, but IF it is a BLDC motor and then need to know the number of poles the motor has, once you know this and the shaft dia. then either Renco or Hegstler offer replacements.