Hi, just got my old Hornet out of storage (for the last 20 years!). Got a new battery and checked it out, regreased etc, all looks good. BUT it slips when taking off and just gradually speeds up, I can hear it is trying to go full speed straight away but something is slipping, what could it be? Motor?, checked the dif and all cogs are still good. How should I start troubleshooting?? ANY HELP APPRECIATED!

Thanks