Problem is there are numerous causes, so the solution is going to depend on the cause.

Is the Riptide a US2 motor and if so do you use the buit-in transducer? If it's a US2, I'd check the fuse in the head.

Next step IMO, is to take the transducer loose from the TM and hang it over the side in the water and see if the interference is still there. The more you can get separation between TM wiring and FF wiring, the better off you will be, both for the test and normal operation. This will help narrow down where the problem originates.