How long have you had it? Does the place you bought it have the expertise to diagnose the issue? Send Maytronics an e mail and ask them for their manufacturer recommendation.
I bought an S-1 and I think it is fantastic, even when my pool looks very clean and I let it do a 2 hr cycle the filter frames come out black and catch so much you can see. I swear by it. When I bought mine they had a promotion where you get an extra fine filter basket in addition to the just the basic screen. I also like that it is self contained and all that it catches never enters your main filter.
let us know how you make out with this.
I know of another S-1 problem where the machine will not climb the walls but have no resolution yet.