Gas driers - how to fix things - Dryer keeps shutting itself of midway through the cycle.

I have a Sears Kenmore gas dryer model #110 70982990 and S/N mj4502425, about 10 years old.
The dryer keeps shutting itself of midway through the cycle. On a 60 min perm press cycle it w..

I have a Sears Kenmore gas dryer model #110 70982990 and S/N mj4502425, about 10 years old.
The dryer keeps shutting itself of midway through the cycle. On a 60 min perm press cycle it will shut down about every 10 20 minutes. I push the start button and will continue for another 10 20 minutes.
The timer still runs to the end of the cycle. I tested it without clothes in it and ran all the way through the cycle without a problem. To eliminate the vent as a problem I have it disconnected. The dryer has been cleaned of lint etc. Thanks for you help.

Based on you description of your symptoms and the fact that it only occurs with a load in the drum, I can rule out timer, door switch and heater and vent related thermal problems as a cause. Your drive motor is worn and is beginning to fail. What is happening is that when under light load, the worn motor shaft bushings and the increased resistance in the motor "run" coil is causing excess internal heat in the motor, which has a thermal overload protector built into it.
This protector is thermostatic and is normally closed circuit until its heat threshold has been breached, at which time it will open and cut power to the motor and heater until the motor cools down. Once the motor cools, the protector circuit will close, once again allowing motor and heater operations. In the absence of any other mechanical resistance causing the excess load on the motor and airflow restrictions, this is all it can be. Your part # 279787 and it runs $128.99 from Sears.
Its relatively easy to install but sometimes while installing it, we find that the blower cannot be removed without breaing it because its on so tight so we have to also install a blower wheel which is part #697772 and its $25.64.
This is really not a tough repair for a mechanically inclined person, but pro labor would range between $80-$150 depending on what servicers in your area are charging. Please let me know if you need more information. Thanks!
Eric.

follow-up comment. I was with the machine yesterday when is shut off mid cycle as i described. I pushed the start button right away and the machine ran for another 15 minutes.
There was maybe a minute or two before i hit the start button. Could the motor have cooled enough in this short time to start up again?

Absolutely. The wait time can be anywhere from a few seconds to several minutes, depending on how hot the motor is.
This is the beginning of the end for the motor and eventually the time you have to wait will increase until at one point, you cant start the motor at all.
It wouldnt be a bad idea to remove the blower duct/cover to check that the blower wheel has not become obstructed partialy which would increase the overall load on the motor. Also check the drum rollers, belt idler and drum seals for the same reason.

I will need to do the work myself, is there a tech manual online or elsewhere that details the R&R of motor/blower? Thanks.

I understand. The great news is that this is one of the easisest dryers you could ever have to work on. First, follow this LINK to download the closest service manual I have for your dryer.
This one IS for a DOTT dryer which is what your's is but for an earlier version so you will notice some differences in the LOOK of your machine on the outside compared to the pictures.
This has all the information you will ever need about your machine. To get to the console screws that it mentions though, just remove the side console endcaps in order to access the console mounting screws. Follow the instruction for removing the top and front panels, then follow the instruction for blower wheel removal on page 16, then motor replacement on page 17 except that you do NOT need to remove any screws from the motor mount.
Just remove the spring clips that you will see holding the motor down to the motor mount. Disconnect the wiring connector, then reinstall the motor.
Rotate the new motor in the motor mount until you feel it lock into place, then reinstall the spring clips with a flathead screwdriver.
Reinstall the blower and belt, put the blower housing back on, panels back on, DONE!