On Friday, September 6, 2024 Model 'N' remote arm #9352 was removed from the NHC right side installed position to investigate  an ongoing issue with the tong motion circuit (no motion on the remote side when handle on operator side operated).

Inspection revealed that the tong cable on this arm have hopped its cable drum and rapped around the shaft of the cable drum. As well, the tong cable had hopped a lower pulley and was jammed between the pulley and casting of the pulley housing. These issues were corrected and arm#9352 was reinstalled onto the right hand position. This repair resolved an ongoing tong motion system stemming from November 2023 described below.

initial tong motion problem from November 2023 when the tong system jammed, operator side arm #9763, remote arm #9342.

Remote arm #9342 was removed and replaced with arm #9352 as it was suspected there was a hopped cable on #9342. Upon removal it was confirmed the tong cable on remote arm #9342 had indeed hopped the pulley. After installation of the "spare" remote arm #9352 that hAd not been installed since previous servicing and should have been completely operational, it was found the tong system still did not work properly.

Upon thorough inspection of operator arm # 9763 it was found that the tong cable was prematurely reaching the end of its travel on its drum causing the inability to activate the circuit. The tong cable was reset on its drum as per manufacture's specs with one full cable rap on the drum and one full pretension wrap of the tong drum spring.

Although this resolved part of the problem and allowed a full squeeze of the operator handle it did not result in transfer of motion through the system to the remote end.

Further investigation continued, separating the operator side arm from the seal tube and testing the seal tube and operator side arm independently. Both systems worked fine independently, pointing to a potential problem between the seal tube and spring loaded coupler on the remote arm.

Remote arm #9352 was removed and couplers visually inspected and end of seal tube on the hot side was inspected and found that the pin in the end of the shaft on the tong circuit was not installed symmetrically which could cause uneven pressure on the spring loaded coupler of the remote arm. This pin was adjusted and all pins on the hot side of the seal tube were dimpled and loctite applied as a precautionary measure.

This still did not remedy the tong motion problem. These led to the September 6, 2024 removal and repair of remote arm #9352. This arm had previously been serviced by a CRL technician in December of 2017 and had not been installed or used since and should have been in operational status. It is still not clear why it was not.