Dryer cutting off mid cycle

Look here for a start.

If it is happening at the same point of time in the drying cycling; could be worn contacts of the timer? New timers expensive. But if one is skilled in electromechanicals, however, it is sometimes possible to repair them by possibly burnishing contacts. The contact that 'might' be faulty maybe the one that controls the timer switch itself ...... that is the contact that switches off the timer when it has completed the timed run.

However if something else, it might be that an overheat switch has become weak and is now operating at too low a temperature at some point during the drying. What is needed if all the obvious clean out things have been done is to trouble shoot the symptom's to find the cause.

There are number of items in the circuit of a typical dryer that could be causing it. Several cabinet overheat switches, timer contacts, door contacts, motor overheat, defective main thermostat etc. etc. So what is needed is someone who is knowledgeable about circuit analysis and is safe with the; Leg A and Leg B single phase (usually

BTW the dryer doesn't have a defective humidity detector does it (The gadget that cuts off drying when the humidity of the clothes falls below a certain level?) just an idea!

It could be the timer. Try running it on a different mode like "timed" and see if it still happens. If it does not happen, I would bet its the timer. It could also be a defective belt switch. Some dryers have a safety switch if the belt breaks, which cuts off power and shuts off the dryer. The switch is connected to a belt tensioner, it could be its loose/intermittent.

Did you also clean the vent on the outside of your house. A lot of crap can accumulate there and it is possible that the vent door(s) on the outside vent exit can be stuck....just more to consider.