Bosch SMS40C12GB drain pump error?

Hi

Got a Bosch dishwasher SMS40C12GB which I need help with please. The customer says it will not drain, and when I attended sure enough there was water left in the bottom. However when I reset the cycle it drained everything. Upon removing the drain pump and testing it I noticed the following and wondered how normal or not this is:

It runs clockwise for about a second, then judders back (anticlockwise) for around 3 secs. It repeats this 3 times and then runs full pelt clockwise (the correct direction to drain). Put it back together and I get it to drain everytime, but as the customer says it sounds ‘sluggish’, i.e when it is performing the above routine. I don’t recall seeing this before, so can anyone shed some light please? Customer says there was an e code but can’t remember the number.

Cheers,

John.