Thank you for the helpful suggestions!!
Our family bought it in 2014 (I think it was new/like new) and it has been knocked about a little. I got a new lens (a Sigma DG 70-300mm) for it in 2017ish but it didn’t work very well on it. The shutter would open but it took it too long to/didn’t want to close. Because of that I stopped using that lens, but that may have done the damage. Not too long after that, from what I can remember, this problem started and I stopped using this camera. I pulled it out the other day to see if I could get it back up and working so that we would have a DSLR to use. I have tried different lenses and just the body…nothing changes. I have disassemble the camera several times to see what I could find. Everytime I have been able to get the aperture leaver back into position but as soon as I reassemble it and press the shutter release it makes a sound like the shutter opening (but it doesn’t open) and the leaver goes back into the wrong position. The aperture control unit seems to be malfunctioning, but I am trying to figure out if it is malfunctioning because of a shutter problem. I can’t find any helpful information anywhere other than the Nikon D90 Service Manual.
I could buy both the shutter and the aperture control units, but I don’t want to buy something that I don’t need. I don’t think the camera is worth what it would cost to take it to a repair shop.
Any other ideas or thoughts?