simpson maxidry plastic door switch broken but complete.Dryer wont start ?

Simpson Maxidry 1000.model 39d36p02. Plastic door switch came off door but still complete and screwed onto piece of the plastic . Have pushed it into the small hole and then shut door but dryer wont start. so even if got new switch (current plastic one o.k.) what is the problem? is it a sensor in the hole near the door?.Would appreciate as pensioner and dont know if worth getting service call or get new dryer. Regards from June.