Hotpoint HVL211 not spinning correctly

My parents have replaced an old Ariston Marghareta with a hotpoint HVL211, i believe for this model they just crossed the Ariston name out and wrote hotpoint in its place

The machine appears to occasionally have problems spinning up – the machine is perfectly level and flat but it still vibrates a fair bit when it does spin.

The main problem we have is that the machine sometimes decides it does not want to spin up fully – it sits there with the drum moving fast enough to stick the clothes to the drum but not fast enough to spin it up

Diagnostic tests carried out
Ran the machine with an empty drum on a spin cycle – this spun up correctly incase the out of balance sensor was thinking it is continually out of balance

Checked the pump – pump clear and shifting water as quick as you would expect

Loaded the drum half full (ie 2 towels, double bed blanket cover) – this spun up fine

Im not quite sure what else to check on this machine, does it sound like this is just merloni penny-pinching at work programming the OOB sensor to be hyper sensative due to not up to scratch suspension (can you tell ive read a fair bit about modern hotpoints)