I've used the MB-10 Vertical Grip on my N90s for about five years. I use my equipment 'moderately hard', I guess. I noticed recently that the thumbwheel for the mounting screw was difficult to turn. It felt like it would make about a half revolution then get very tight, over and over again. Thinking that the mounting screw was perhaps bent, I posted a question about it on the Nikon-Digest. The answer I got surprised me: a kind soul said the same thing had happened to him, and it turned out to be loose screws in the MB-10. I set out to repair mine, and took a few photos to illustrate the problem (excuse the quality, I really should use a tripod for these macro photos).

First, you need a tiny, high quality Philips screwdriver. My inexpensive set of jeweler's screwdrivers wouldn't touch the screws that Nikon uses on this thing. When I located my Xcelite "00" screwdriver, I first removed the seven screws that are on the top plate of the MB-10.

Next, remove the two screws that are near the vertical release button. Now the top of the MB-10 can be removed (there will still be some electrical wiring between the two pieces).

With the guts exposed, you can see the plate that holds the thumbwheel assembly. Remove the five screws that hold it in place.

When you remove the thumbwheel / plate assembly, turn it over and examine the three screws that hold the plastic thumbwheel to the 1/4 - 20 camera mounting post.

If the screws are backing out of the assembly, this is the source of the problem. If you are missing any of the three screws, check the cavity below where the plate is installed. One of the people that suggested this problem to me said that one of his screws was rattling around in the plastic cavity. If you lose all 3 of the screws, the rumor is that your MB-10 must be 'sawed off' of your N90s!

That crescent shaped scar in the cavity is the source of my 'symptom' of the thumbwheel 'dragging' every 1/2 turn. I guess it was actually dragging every 1/3 turn, as the extended screw heads gouged into the plastic.

I used a bit of model cement on the screw heads when I tightened them. It would probably make more sense to use a product like 'Loctite' on the metal screw threads where they mate to the metal assembly.

Reassembly is essentially the reverse of the disassembly process. I am by no means a certified camera repairman, let alone an instructor in the field. I offer up this webpage for those brave enough to try this themselves, and as a warning to those who wonder why the thumbwheel on their MB-10 is 'dragging'. No warranty, express or implied, is intended by the author of this page, blah-blah-blah.

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