Older Beachcomber Model 550 not heating

[JerryR]

I inherited a 1997 Beachcomber Model 550 that is not heating but I wish it did.  Here' what I know:

-the motor is running normally and the pump is working fine, both are brand new
-there are no error codes on the topside controller but the red heating status light does not come on
-when powered up the actual temperature reading is 54F now.  Was 56F yesterday which I'm assuming means the water temperature sensor is working
-the temperature setting on the controller is set at 100F.  I am able to raise and lower this setting but nothing changes in terms of operation
-heater element resistance is 15 ohms but no 240v at terminals 
-the heater relay on the circuit board shows 253 ohms but is not closing which explains no 240v at heater element terminals.  Manually closing the relay gives 240v at the heater element.  Having trouble testing for 120v at relay, not sure how to do this.
-with the power off, pressure switch is open.  Not able to confirm if the pressure switch is closing when powered up, not sure how to do this either.
-removing the pressure switch/high temp sensor connector (4 pin combined connector) from the circuit board before powerup causes a Sn fault
-checked the high temperature sensor for continuity, not showing any resistance.  I understand Ohms should vary with temperature, ie. higher when colder and my guess this is the cause of the problem.
-circuit board looks ok, ie. nothing burnt, no cracks, continuity in several circuits I checked..

Any insight is appreciated not to mention some advice as to where a guy can find parts for older Beachcomber hot tubs.

Thank you.