Gutter vac keeps cutting out

Evening folks..as the title says.. my 3000watt gutter vac is playing up. 

It seems to work for little while then 1 by 1 the vacs turn off and it feels hot. 

I don't run a filter either. 

What could be causing it to over heat...or is it the vacs on its way out. 

Thanks folks 

Could well be a slow build up of muck in the motors but without being able to see it very hard to say. What make is it