2 belt dryer problem?

I had one of my belts break on my 2 belt electric Maytag DE 500 clothes dryer. So I got new belts, they are exactly the same size as the old belts, but the outside belt seem to put a lot of tension on the spring, while the inside belt is loose (slips). The inside belt is the belt on the electric motor pulley. It was the outside belt that broke. Why doesn't the tension equalize in the belts? instead of outside tight and inside loose. I re-greased that slider thing behind one of the outside belt pulleys, so that does not seem to be binding. I am stumped why this thing does not go right back together, but I am wondering if the problem is not the belt itself, but whatever caused the outside belt to break in the first place????????/