Oh, I agree. The electrical variable I mention is in the subject post of this thread, a diagnostic owner made, not your experience as a professional replacing a confirmed non-functioning fluid switch. I trust you are well skilled at separating the electrical from the hydraulic symptoms before actually laying hands on your 12mm wrench. Much easier standing up, too.

The mysterious need for a new solenoid to acclimate itself to its new fluid environment would suggest a bit of clotting in the machine's life blood. Though I haven't any direct experience with the delayed action after replacement, I've seen the passages through the casting to the valve body are long and thin, and separately found the waste oil after a high-mile tranfusion to be laden with the clutch particles of too many ignored fluid services. Just another guess at the behavior you note.
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Art Benstein near Baltimore