I have a martag dryer that is spinning but there

This is usually a repairman problem, because it's technical... and dangerous (electricution hazard). This is the usual suspect on ANY electric dryer that runs, but has stopped heating up.

Think SAFETY FIRST. Don't rush. Your dryer doesn't care that you treat it nice... it can shock you! Now, let's do it.

Here's something you can check on your own... BE CAREFUL!
1. unplug the dryer, remove air vent.
2. remove back plate (12 to 20 small 1/4" screws)
3. find schematic diagram (paper folded up & stored in back)
4. locate THERMAL RESISTOR (typically, there are 2) on paper, take notice of wire colors on each end of it. (the diagram states wire colors, so you can find them.. the part is typically grey or black, and rectangular in shape.. about 1" or so in length). locate the thernal resister(s) now.
- - typically, there's one on the vent and one on the drum (HOT spots)- -
5. take the 2 wires off only 1 resistor ONLY and join them together firmly (using the 'metal loop' ends), be sure they're away from any metal (shock hazard). you've just learned to by-pass a possible bad circuit.
6. now... your new connection is hanging in mid-air. plug in the dryer, choose a HOT cycle, & start it up. wait 5 seconds, open the door. Is it hot?
YES - unplug the dryer, remove the Thermal Resistor, go buy a new one..(take it with you, to match). Install the new one, re-attach wires, put the back on, attach the vent, plug it in, use!
NO - unplug the dryer, put the wires back on that resistor.. find the next one... repeat steps 5 & 6 as needed.

If one-at-a-time didn't work, by-pass every one.. being safe that nothing's touching anything else. repeat step 6.

At this time, hopefully it's working, and you're off to the store. Did you remember to unplug the dryer?
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FYI: the wires on the resistors are interchangable.. doesn't matter which one on what end... as long as they are the same two you took off that part in the first place.

If still nothing, put all the wires back. call a pro.

In any case, while the back is off.. clean out the fuzzies. Lint collects everywhere... usually why thermals overheat & quit... and can cause fires.

Good luck.