Hiya,
Having had a 2520 in the past, I would like to suggest that your issue is the tractor is like all other 2x20 series, far too light. I had all sorts of traction issues when I first got mine, the tires would blow off and dig a trench so easy when pulling out of a material pile or even box blading, the tires would slip.
I resolved the traction issues by loading the rear tires with beet juice and adding a set of weights. It was still a bit light for loader work in loose or rocky soil but it was a vast improvement. I used it with a RFM for my lawn, with the added weight, it didn't slip the tires and ruin the lawn even in wet grass.
If you want to add weight to the front, you can put 3 forty Lb suitcase weights on the frame and the loader will clear them. I used that with my loader plow to keep the front wheels on the ground when in float.
If your doing all loader work, and your issue is that you have trouble backing out of a pile with a bucket, you can swap the wheels so that the tread will be reversed, giving you a lot more traction pulling out of the material pile.
My 2 cents,
Tom