I was offered a Tench upgrade again upon return to Midway (late April 1945). Again, accepting meant CTD whenever I tried to start a patrol.
Sadly, I had to re-load from just before arrival and refuse the upgrade.
I'll be setting aside SH4 for a while once I finish winning the war this time. Going to concentrate on some other hobbies for a while and then see what's up. Thanks for the hard work and effort, modders, until then!