polar 76 EM clamp bounces on return.

Hello,
I have a polar 76 em
My problem is: The clamp comes down so hard it bounces and when it returns it bounces even worse!
The clamp does this with or without the pedal, so I don't think the pedal adjustments do anything. So to be clear if I just hold the cutting buttons the clamp will slam down, the blade cuts fine, and then the clamp slams up and bounces hard.
Any suggestions? and like anyone if there are manuals out there i'd like one!

Thanks in advance...
Pete.

 

Hi Pete just seen this post. When I am in work shop I will send info on how to adjust speed of clamp