You have completely lost me now. You say you swapped out 4B but do not see 4A or 3 recs. They look exactly like 4b and they are on SCR panel up on top. You say you have 17 volts at the bolt on the 1rec where the 3rec and another cable are(T2) and 0volts at the A1 connection right beside it which means the power fuse is blown or cables are not hooked up correctly to it or on contactor panel. Start with that and go from there.
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