If you are close to Stam, I would say that he is your best bet at saving money and doing it correctly {and 'doing it correct' is how you save money}. He has proved [to me, here on forkliftaction.com] that he knows what he is doing, and makes the effort to do it correctly.
The forward contact has to make good connection when "at rest" for the power/current to flow in reverse (and vice-verse). My WAG has it that you need to replace as complete units both directional contactor assemblies, as they are most likely so worn out as to be sticking. if this unit has a battery over 7 years old, I would say this may be time to consider a much newer unit, not so much because of the cost of -this- repair, but just the overall age of the unit. You/I would only be able to sell the unit for scrap metal weight.
"Cathodes" are the negitive side of a conductor or semiconductor, these SCRs and large diodes have a pigtail type of cathode, and a stud type of anode (anode being the positive connected side) that is screwed into an insulated from the frame, metal heat sink.