White westinghouse dryer won't keep running after the start button is released

It sounds like you may have an open motor winding or a safety open due to dirt buildup. The only way to know is to use a meter to find out what is happening. You can use an ohm meter to see if the safeties are open. They are oval shaped t-stats screwed onto the sides of where the heating element is located and where the air ducts are. These t-stats have two wires plugged onto them and are supposed to be a normally-closed connection. Most are wired in series with one another so that if power is stopped at any of them no power will flow through the circuit. Occasionally you will have resettable t-stats that have a reset button on them that you press to reset and some burn open and must be replaced. The ones that burn open are usually near the elements and you have to clean out deposits to get the drier to work again and then replace the $35 t-stat. Make sure to scrape out the ducts well and wash the parts to get out all deposits. Sometimes these deposits will be an inch or so thick and fill a five-gallon bucket. Vacuuming will not work except on motor where dirt can keep it from working, as well. Hope this helps. DrTom4444