Priscilla
I will take your request as a compliment. I do not have parts for the Hotpoint Hallmark. I am not an appliance guy at all. My profession has to with the servicing of cars. The Frigidaire Flair is only a hobby. My parents had installed a Flair in 1963 in our home, I was seven at the time. We cooked on it with no problems up to 2008 when we had to sell our family home. I had extra stoves for parts and brought them with me, and installed one where I am living now, and since then found and bought 4 more. So I have a total of 6 Flairs. 5 are 1963 and one is 1964, 5 custom imperials and one custom deluxe, all the dual oven 40 inch type.
What I have learned mostly, is from working on these stoves and from people on the website. This is only a hobby and not my profession, so I am still learning, but give advice to the best of my experience, and every once in a while, some one will come forward with additional information, which helps all of us.
At this point, with the heating problem, I would suggest the switch and the element to replace to get it working properly. Both the switch and the element, you can still get new from Repair Clinic on line, you can buy the parts and have them shipped to you. I believe that they no longer carry the oven switch and thermostat. The oven switch and thermostat, you have to rely on people like us who have old used parts that you can buy and use, and in this case, you can actually send the thermost and switch and have them rebuilt. A rebuilt thermostat and switch can be hard to find and become expensive, I know there was on ebay for a buy it now price of $99.00.
If you want to take some time and visit the Repair Clinic and see what your options are, and if you want to try and locate a rebuilt oven switch and thermostat, give it a whirl. All I have are used parts that I would pull from an old working stove and send to you. One more thing, remember, diagnosing anything, and based on what someone says that is happening, and with out seeing the unit first hand does not always constitute a final diagnosis, there could be other factors involved, like wiring, grounding, short circuits, connections that could make operations fail. Just something to think about.
Do some homework on your own, and then let me know if you really want the parts, because I do have the used switch, thermostat, element and switch for the infinite heat, oh, and those same parts right now are on ebay too, so you might want to take a look there.
Good luck and keep me posted, Be in touch
Tom Nichols