My Jacuzzi Essense hot tub is not heating properly, everyday I go out to check the temp. of the water and it is usually too low and the digital readout says FL. If I jump on the floor next to it this seems to trigger something and it starts working again and will heat up for awhile until it goes to FL again. This is gradually getting worse and happening more often. Is this the Flo switch?

Yes, it's probably the Flow Switch. It's usually easy to change.