Here are your parts
Replacement parts for FRIGIDAIRE GLHS67EEPW1 Frigidaire/refrigerator | AppliancePartsPros.comHere is the tech sheet
http://manuals.frigidaire.com/prodinfo_pdf/Anderson/240389624.pdfThere is no timer in the unit. The defrost is controlled by the control (Genesis) board.
Why do you think it is the defrost thermostat that is shot?
Have you tried forcing a defrost?
And then measured the thermostat and saw that it was infinite ohms (open) when frozen.
Looks like the original thermostat is hard wired in.
So you cut off the wires to it.
Slip the white heat shrink over the wire.
Cut back the insulation on the wires.
Then crimp the connectors onto the wires.
The heat shrink is then placed over the inline connectors and shrunk using a heat source.
Tried to find directions with pictures for you on the net without any luck.
Perhaps you will have more success.
Since you probably will not have a set of crimping pliers you would probably be better off using a couple wire nuts.
Then using a zip tie to attach them away from the heater with the open end facing down so water cannot get into the connection.
Some people also like filling the opening with silicone sealant as an extra precaution.
If you want to do this do it after you have checked that the defrost works.