Hi and Welcome to Just Answer,
Ok, let's take a look at this;
I see Smithy Has OPTed Out, I will try to help you on this
Unfortunately when dealing with gas driers there is so many possibilities on what could be the problem, from the thermostat, to the igniter, the controller, even the door switch.
You would be far better off contacting a repairman on this, due to the fact that we can change parts until you double the cost of the repairman.
But I would start with the Thermostats and Igniter first if you wish to try to repair it yourself.
Here are the parts Break down and a site to get the parts
If you need more help Let me know
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