You could try holding down the 2 mouse buttons when you turn the machine on. Then go to the option that allows you to change the chipset used to 'original' or 'enhanced'. If that doesn't work you could look on Aminet as they have loads of degrader type programs that make an A1200 or A4000 think it's running Kickstart 1.3. Finally if you go to
www.whdload.de they'll have an installer for hard drives. This might work.