Picture shows Drill Jig and initial test holes to gauge hardness /machinability at suitable depths. Main and starter gears flanges and couplings were removed

Damaged section removed and cleaned up.  Dummy block made and fitted – blued in bottom to ensure good contact. 3 blocks in total made here. 1 block test dummy piece for profile and geometry. 1 block as used / fitted. 1 spare in case of gear cutting or heat treatment problems.  Half hole perforations visible are drilled out and temporary locks, dowels and unbrako’s installed for gear cutting.Block then removed for heat treatment, refitment, gear grinding etc as follows. Unable to heat treat section in gear as damage, embrittlement and softness would occur in adjacent teeth.

Section after Heat treatment [case hardening]. Section required fitment and reworking of butt face contact area as some movement - typical / expected and allowed for in heat treatment occurred. Piece being installed by Metalock / Masterlock method. Higher [harder] grade pads used in caulking process, high tensile MN555 Metalock keys used throughout. Some 50 taps, 12 carbide and 45 HSS / normal drills used on this small section – tools resharphened continuously.  Section fitted prior to secondary finish grinding.