Oven temp will not rise

Here's a list of problems that have been happening. *The oven will display "locked". The oven will not work. -the door can still open and close -the lever is not the problem because it is still able to move to both the on and off position. (lever is manual) Broiler works awesome. Bake won't rise pass 170 degrees. -the bake element is fine. -sensor still works Clock will change the time -sometimes we will notice that the clock on the stove has changed time. I'm thinking the clock/ control board is the problem. Calling the repair guy is on my back burner - right after buying a new oven. Why? Because one they all charge for the initial coming out, we pay for the part(s), and we pay for every hour they are here. Wouldn't be to bad if the prices weren't so high. I'd rather buy the parts and fix it myself. Did so just this year with my fridge. Would of cost us a bunch for a simple fix. Sorry to be long winded but I just want a second opinion before I moved on to my next option. Aloha and Mahalo for all your help (goodbye and thank you) -moana