G.E. gas dryer will not stay running

I replaced broken belt, tensioner, rear bearing assy and sliders, now when i turn the starter switch the dryer will not stay running, as long as I hold the switch to the right it will run and the gas will light up. When I let off the switch everything shuts off, i checked the door switch it’s working fine. this problem started after i replaced the parts, what could i have knocked loose? i looked for loose wires found none. please help. tks skonny.