services of rebuilding and repairing, and providing technical assistance in maintaining and operating rubber and plastic extruding machines, and associated equipment, including plasticizing screens, extrusion dies, crossheads, pulling machines, cooling tanks with material pullers, belt and roller conveyers, plastic feeding hoppers, thermoforming machines, corrugators, extruder screen changers, coolant pumping units, rolls and roll stands for extrusion dies, pelletizing machines, cut-offs and slitters; blow machines and associated equipment; and spare parts and components for machines