signature2000 ind. montgomery ward tmo-339-54a?

mower did run when clutch was relasted,sanded&painted it now when started it shut off when clutch is relased,rebuiled carb. replaced one interlock switch under dash. check all wireing for shorts. i would like to know if the switch the clutch engage is a locking switch or not,and why whenever i relase the the clutch the mower stop running.