As I purchased the Beko washer and dryer, I felt I should do the right thing and also buy the stacking shelf to make sure they stack correctly. I couldn't figure out why the drawer was out of alignment. I felt it was faulty and was going to return it, but when I had a close look at the runners I realised that the mechanism had been assembled incorrectly. There were two assembly faults, one was that each runner was slightly out of alignment with the other due to incorrect screw placement, and the second was that the entire left runner was assembled wrong. I was able to rectify both issues and fit the unit to the washer. Hopefully the dryer and washer don't suffer from similar poor work practises at Beko!