GeckoDrive: seeking practical advice about the Big Capacitor !

I now have a Gecko Drive (G201) driving a PacSci motor which is rated at 5 Amps/Phase in a parallel connection.

The Gecko is set to 5 Amp (using a 120K set R) Supply Voltage is regulated 36 Volts at 8 Amps. At the Gecko ( 6 inches from it)
there is a 15,000uF 50 Volt Cap.

Under no load conditions the motor can reach the speed required, but under load it reaches a point where
it makes a horrible sounds and stops rotating.

Under normal circumstances if I could increase the Voltage to (say 50-60V) I feel sure the motor would continue to rotate.

This design does not allow greater than 36 Volt.

My Question:- I have space for a 56,000uF 50 Volt Cap. . Does anyone have experience of the result of increasing the Cap. Value by almost 4X , would it help solve the problem or is it a waste of time
?

Best Regards
Hans W