Final comment: it’s been commented on this site, and others, that members often fail to state the results of their attempts with repair issues; thereby failing to extend their findings, which may be helpful to others. That said, I offer the following.
I disassembled / reassembled control unit 4 more times. I finally discovered (what I believe to be) the correct alignment of he (3) roller bearings in the shift lever cam / shift lever and driveshaft plate support. After reassembling all parts, I bench tested the operation of the control, SUCCESSFULLY rotating the full range of the spindle 4X with shift and throttle arms operating in proper sequence…..as well as, proper shift disengagement for neutral warm-up operation. I then took the assembled control to the boat for installation. I successfully tested operation again before installation. I then attached the shift and throttle cables before installing the control to the boat. Recall, the control unit is a concealed (flush) mount, which requires cable attachments prior to installation. I decided to make one final test before final installation. Although the throttle arm rotated properly, the shift lever was no longer operating. Btw, the cables were moving freely, and should have no influence on the operation of the shift lever…..other than potential hard operation….which there is none. Hoping for a miracle, and regardless of seeming failure, I installed the unit. Not surprisingly, there was still no shift control, although throttle continued to function well. At this point, I can’t imagine how the roller bearings could be installed in other way that what I did for proper function. Improper positioning will not permit the parts to go (slide) together. That said, it’s clear shift engagement is clearly a function of the positioning of the roller bearings in the shift lever cam and contiguous parts. So, I’m at a dead-end as to the proper completion of the repair. I give!
Not certain if the most recent lack of response from members is due to disinterest of the subject or lack of knowledge. I hoped I could solicit the help of someone with the knowledge of how to properly diagnose and repair my control unit. That said, thanks to those who offered what they could.