Why Hotpoint wf321 1200rpm stops & starts in the drain cycle?

I have a hotpoint wf321 1200rpm & Had central heating installed and the engineers had moved the machine in and out 2/3 times and after couples of washes the machine now keeps on cutting off in the spin(drain cycle) and few secs later starts and cuts out as soon as the spins starts to rev up........ any idea why please help!! I have open the front pump filter and nothing blocking it.