When I enter distance, speed and time in my Spprtscraft TX4.9 or starts out fine for about 15 seconds then it completely stops and

Margarita jones, August 2017

and........what?

Doing the Google search you could have done gets me to some interesting results, all centered on the speed sensor:

https://howtomendit.com/answers.php?id=275962

https://www.justanswer.com/fitness-equipment/4us7y-sportcraft-tx-4-9-set-speed-treadmill-turns.html

Acp, August 2017