Hi, I have a PR903 which preceded the 04 Series. I have never had a problem with the panel memory holding registrations/presets after turning off. I thought Custom Presets were constant as well. I know some Technics models only hold memory for 80 minutes. The 604 may be one of them. Check the manual for confirmation. If not, you may have to save to a disc for future recall. I am sure there are SZ members who have the same or similar models who may be able to help.
Ray