Anyone with a Minolta 5400 II had this issue?

My scanner is doing a couple funky things and I'm not sure where I might find any sort of help these days.

First thing is the negative carrier seems to be casting a shadow across the negative edges where the plastic frame dividers cross. The negative carrier for this scanner has plastic that goes all the way across in two spots and then about 1/4 the way across in one spot (see here). I'm pretty sure it's the scanner and not my negs because I can clearly see it on the scans from positions where the negative carrier goes all the way across and I get a noticeable (but less obtrusive) shadow in the area where the plastic does not cross the entire frame. Here's an example... along the top you can see the scan has a dark shadow. I've had this scanner for 8 years or so now and after putting in back into service this year (after ~4 off) I'm noticing this. I don't see this on scans from a few years back.

Second issue is that every once in awhile it makes a very loud whine for a few seconds right before starting the focus routine. There doesn't seem to be a specific frame that this happens on and it seems to be pretty random.

How was the scanner stored during those 4 years? Dust on mirror/lens/sensor can introduce reflections. I'd clean the negative holder and open the scanner and check the light path for dust. If v2 is anything like the original Minolta 5400, access to the mirror and the lens is very easy. Sensor can also be removed and I didn't find repositioning/aligning the sensor after taking it out too difficult (I could even achieve better alignment than the original).

It was on my desk for a couple years and boxed up for a couple years so dust is likely. In southern California, anything short of hermetically sealed collects dust like I collect cameras. Does the service manual have instructions for this? When I glanced over it I found it incredibly lacking in detail. As someone who basically serviced electronics as a job (until 'rona killed my bsuiness) I'm comfortable having a go provided there aren't any gotchas.

I doubt that V2 is much different than v1 under the cover. Removing the case is all you need to do. Then the mirror, lens and sensor are all easily accessible after you peel off (mild adhesive) black plastic cover that shields the light path. There were no gotchas on Minolta 5400 V1. Compared to some other scanners, getting to light path elements of Minolta 5400 is child's play...

https://www.closeuphotography.com/minolta-dimage-scan-elite-5400-lens-removal

Cool, thanks for the link. I'll take a look at this soon.

I figured out what the problem is... this shadow is formed when the film borders on the left and right are not full covered by the frame dividers of the negative carrier. If the negative carrier does not have any film base showing through along the divider edge, the shadow doesn't form. I'm not sure how I never noticed this before but after cleaning the scanner lens and mirror I see no improvement. The mirror was a bit dirty though so it was good to get it apart and cleaned up.

Yes, that is a typical case of internal reflections. Noticeable on dense part of the frames that are close to the unexposed (unmasked) parts. Usually if the film has relatively clear base the problem is more pronounced.

Some scanners are better than others in that regard. For example, the slower (because of weaker light source and lower sensor gain) original Minolta 5400 is better. You can scan even dense negatives with unexposed part of the negative in the frame with no reflections (shadows) in the image area. Some faster scanners are notorious for reflections and there is no way to scan the part of the rebate of the film especially if you have a dense negative. The problem lies mainly in the sensor cover glass that doesn't have antireflective coatings. Line ccd sensors that you find in scanners are off the shelf components and you can only make a scanner faster (without introducing additional noise) with more light hitting the sensor to get shorter exposure. More light - more reflections/flare. If the light path is dirty the problem is even more evident.

The Nikon Coolscan 8000 that I had drove me nuts because of flare. At the end I decided to remove the sensor cover glass. I tested the removal of the cover glass on a cheap flatbed ccd sensor with great success, but as things go, I then damaged the CS 8000 ccd sensor in the process...

A number of scanners that I had were quite flare resistant, I was most impressed by Microtek 120tf. You could scan negatives with sprocket holes included with very little parasitic light in the surrounding areas. Not as good as a drum scanner, but compared to a CS 8000 it was a LOT better.

Examples of scans with "uncovered" film borders:

(Minolta 5400)

(Canoscan fs4000us)