Larrs Heater Part Question

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Went to diagnose a Laars Lite2 pool heater only to find the 120/240vac Conversion Plug resistor burnt. The heater is wired in 240 volts and this plug was in the blue side which is correct for the 240 set up. I'm wondering if I were to convert the heater to a 120 voltage setup can I then plug the conversion plug in the 115 V direction. Plug #s on the board are e237500 which then comes down to a new part # of Ro336900. So the question still remains if it'll work on the 115v side after I convert the heater to 120v.
Also, here is a picture of the wiring diagram for the transformer showing the 120v wiring but just to clarify, WHEN I wire it for the 120v configuration one leg gets a hot wire and the second wire I presume gets a neutral ??
Laars Vac Conversion Plug 115/230 | R0366900

 

[wireform]

Bumping with a few new pictures.
So the transformer is the one I pulled out and need guidance to make it work on the 115v side of things. Don't understand what wires get joined so please explain this to me.

 

[wireform]

Found the installation manual and this page explains the difference between 230v and 115v connections. If I'm understanding it correctly the difference is on the board by the two connections of the "power in". In the 230v setup it would be L1 and L2 both hot legs where as in the 115v setup the left would be "W" which I interpret is a neutral wire and the right terminal is a hot leg, then I would plug in the conversion plug with the white side for 115v board control.

 

[wireform]

Update:
Heater is running with the conversion documentation above.