Early model machines have a spring suspension and are prone to spring breakage. Your machine can be converted to use the new style of modular rubber torsion mounts which was a very good improvement. This kit is everything you need to change out one corner of the screener deck suspension. 

4 Kits would be required to update the machine completely. These parts will clamp in place of the springs.  The torsion blocks are replaceable separately and unless overloaded (dumping too fast) last much longer.

Thomas Part number U-2848 Kit Shaker Suspension.

Individual Torsion Blocks for replacement are Part Number 48120.