Ah, I haven't experienced that yet ... I have some rolls of BW that are about 10+ yrs expired in the freezer.
You can look through the shutter while the back is opened and kinda guessimate how the shutter is working.
Ah, now I know your name.
Hmmm, I did not notice that post on the FB page ... you may not get the best reception as a newbie but they all have good intentions.
Yes, the first step are the tools.
WorkTable by Dennis, on Flickr
Hmm, under exposed.
So this just happened recently (last two rolls out of x)?
I wonder if there is a mechanical failure of shutter (I do not think that the aperture would be stuck).
You are at the best time in life to take this on ... heck, you built your own guitar !!! and you can play it (I did buy a Fender guitar but I could never get the hang of it). I spent many years breaking stuff, before I could acutally fix them, so do not be afraid ... and you learned film...
Scotty and I (and most likely some others here) have been in the photo industry (he still is), so this is not something that unusual in our experience (mine was 25 years ago).
When the film is wound against its natural curvature it causes stress on the gel and backing ... though you are correct...
As Nikon mentioned ... if you pop down the focus screen. Put it in a safe place. You will see the light meter needle at the top left. Carefully examine the needle movement above the plastic number plate ... lightly try to blow out that area.
Changing Focusing Screens in the Nikon FM/FE/FA