Congratulations on your newly acquired CD5 and Flatcap 2.
I know you are asking about the puck. But, if you haven’t done so already, please be sure to remove the second transit bolt from beneath the player, as well as the one that locks the drawer. (By mistake, I didn’t and damaged mine.)
I have a CD5 and HCap combo, owned it from new in 2003. Naim replaced the mech and serviced it back in 2020. Great service as I thought it was dead in the water. Luckily they were still able to sort the mech and I can get a few more years out of it. Still sounds lovely and stands up well to my Innous Zen mini Streamer. Different presentation but just as good.