Anyway I have this dryer that I can not get to work right. The heating element will come on but only when I put a jumper wire from the high-limit t-stat to the metal vent pipe.
Do not understand why you would do this.
The heating element should not be grounded, it should be wired between L1 and L2 not Neutral/ground. You are asking for an arc and spark. Perhaps that is your problem a grounded element.
Open it up and make sure it has not warped and is touching ground

But the element is only getting 120v, not the 220v it needs to work.
The element will heat on 120 just not get as hot
How do you know it is only getting 120.
Did you measure across the contacts going to the element. Note you do not measure to ground.
Also have you checked your power at the plug. Often half the line can drop out without actually tripping the breaker so you end up with only 120 at the machine. Depending which side drops the motor will run but you will have no heat.

I have not tried to check the house side of things, but thats a very good idea. Also I was not trying to short out the unit by placing the jumper from the t-stat to the vent...the thing touched it by rare chance and got itself turned on. But that really made no sense to me. There is nothing that is visable that is wrong with the element and it also ohms out. And the 3 position rotary switch was change out recentaly and also the thermo fuse was tested and ohmed out. All the parts are making the right test, when tested but yet we have no heat and I really think this maybe a house issue because it was for rent awhile and he had some problem where the heat shut down and lose power and then "it just came back on a couple days later", maybe these two problems are related. I will check this out as well as anything esle anyone can offer up for me to look at in the morning, so please respond Tonight! THANKS A TONNNN!!!