Agree with Stackerhacker that each manufacturer is different. Don't know what truck you are working with might be worth contacting the manufacturer.

I have the Test Procedure from a Clark 1500kg electric counterbalance to hand and easily available if you want to e-mail me with contact details, if that would help... they quote 25mm in 5 mins is acceptable with 50% maximum load, any more than 25mm requires further investigation.

Not even sure it would be picked up by lots of LOLER examiners (particularly from an insurance based background), despite the requirement that the competent person should have enough practical and theoretical knowledge and experience of the lifting equipment to enable them to detect defects...but happy to stand corrected.