Supporting these loads without assists is consistent with muscle and tendon fatigue related injuries such as tears, strains, sprains, tendinitis, rotator cuff tears, and epicondylitis. If counter balances are used additional weight could be added to the gun which would provide additional mass to help absorb the recoil of the tool. Develop a different system for marking the slabs. Use of a marking tag which is nailed in place using different type of fastening tool should reduce the stress of the task. The Hilti DX36M weighs only about 5 pounds, can be used to attach metal tags to the slab, and when equipped with a magnetic tip will hold the tag in place which should allow the use of both hands to control the tool.
Employees are wearing, what appears to be large, thick leather, gloves during the operation.
Gloves should be made of a material which increases the coefficient of friction between the hand and the load surface. This will reduce the hand and finger force required to perform a particular repetitive task. If the thickness of the glove is necessary because of the heat generated from the slabs experiment with a fastening system which might be able to increase the distance an employee stands from the slab. Using an overhead support and an Hilti pole tool should allow employees to perform the fastening or imprinting tasks while standing farther from the slabs. Much of the stressor to the fingers from the use of thick leather gloves is found in the non trigger hand which must activate the secondary safety of the imprinting gun.