simpson esprit 750 does not agitate?

the machine fills, commences agitate cycle then stops. Timer takes it thru to next cycles. It empties, fills but does not agitate on any stage of the cycle. Sometimes does not do final spin. the problem is intermittent. It was "messed up" last nite and earlier this morning and (3 hours later) now seems to be operating as it should. Help.
Only thing I have noticed is that the barrel seems very mobile when I open up the lid and try to re-balance the load