I'd suggest calling Radio Sound and asking them about how to manually eject a disk (I've got to believe there is a way to do it, but the H-D shop manuals don't go into any detail on the internals of the radio). Call or email them here:
Radio Sound Customer Service
1-502-267-6768 or toll free at 1-877-655-9421. Monday through Friday 9 AM – 6 PM EST.
E-mail: customerservice@radiosound.com
One piece of advice I'll throw out which may or may not apply in these particular cases is to not attempt to play homemade disks with stick-on labels. Play commercial disks, use special disks and a printer that prints directly on the disk, or just use a marker. The stick-on labels have caused issues in all kinds of players, from cars and bikes to home systems and computers.
Jerry