I was given a used Acura 5 person hot tub. Not sure how old it is, but it hasn't been used in several years. I wired it for 110v. Everything seems to work except for the heater. The manual shows it can be run on 110v or 220v. Could the voltage be the issue? I have the heater coil out of the unit right now. Is there a way to test it using a multimeter or something else? I don't want to replace it if it's in working condition. Thanks!