Track Marshall 55 Clutch issue

[Beeman]

Hi all

Recently purchased a TM55 with a 931 prefix on the serial number

It’s a lovely machine, however there is an issue with the clutch.

The pedal feels ok and return spring is fine, the pedal goes up and down when stationary, but when driving the clutch pedal doesn't always come back up? Any ideas?

Thank you in advance