Emco F1 Woodworker change of RPM


Hi All,
I've got an Emco F1 Woodworker in quite good condition. I assumed, that I just need to change the beltgears between electricmotor and spindle to change the ratio from 8000rpm to 2000rpm. Today I disassembled the millinghead and it comes out, that the drivegear from the electricmotor can be removed. But the small gear on the millingspindle looks like it's an integrated part, so It cant be changed.

I thought I read that It should be possible to change the two gears. Is there anybody who has changed the RPM at an F1 Woodworker successfully?

I would like to mill aluminium, but with a 4mm mill it's almost not possible due to weak spindle drive on the woodworker.

Looking forward hearing from you.

BR Chris