Nordictrack 18 watt MultiFit controller is currently unavailable.

Although you can purchase the NordicTrack 50 Watt Controller which will be compatible

See NordicTrack 50 watt controller 312810

https://fitnessdoctor.com.au/products/nordictrack-50-watt-multifit-controller

New NordicTrack Treadmill 18 watt MultiFit controller.  MC2100-ELS18W

This controller will suit most NordicTrack treadmills that do not run a touch screen. 

Please note this controller does not come with warranty unless fit by a Authorised iFIT Fitness Repairer- let us help email us on info@fitnessdoctor.com.au