HELP! How to fix my AEG washingmachine, model L7 4950? "E-20"?

My AEG washingmaschine refuses to start the centrifuge part of the washing cycle. I washes OK but when it comes to the centrifuge at the end of the programme it beeps and says "E 20", and I haven't got the instruction-book anymore.

I recently moved the machine to a new place in my house but the problem started before that. Now it seems to be (almost) permanent, and yesterday it didn't empty out the water either, and the clothes were of course soaking wet when I opened the machine. Also the machin started to smell a little bit burnt, I think (?) What should I do?

DATA: AEG Electrolux Lavamat. Mode. L7 4950. Typre HIO64323. Ser.No. 750 00028. Prod. No. 91452660800. Silent System Plus.