I bought my mixer after being flooded in 2007 and have only just got around to using it. I have only tried making a sponge mix using the K beater and the switch just switches the motor off whatever number the dial is on. It either doesn't switch on at all or goes off almost instantly. The pulse works OK as do the other attachments.
Have you tried using the 'P' or pulse button? The machine takes a little time to 'warm up' to speed, so seems like it doesn't start but leave it on the speed you want for a few/quite a few seconds and see if this works. I just bought one and used it tonight and this is what happened. Yes, it seems weird but it did work.
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