What model of Brother do you have? I have the 1500 ps and it's simple to take the housing off . It's all mechanical so very easy to maintain and clean. I would suggest not taking the turn wheel off. It's very tedious to put back together and usually nothing there that needs attention.

I just Saturday took my Juki 2010Q into the shop for service. Always get annoyed when I have a problem I can't fix myself....but then I thought - I wouldn't expect my car to run forever without professional service and tune up. So why do I expect my Juki baby to?!

Watch some of the Brother repairs - I wanted mine cleaned and the thread taken out of the flywheel. There's a small breadboard connector that needs to be taken off, and I refuse to touch those as I have accidentally broken wires.
(I will attempt to fix almost anything that doesn't involve electricity or I can disable while working on whatever)

When I got the machine back, the 4 positions for the feed dogs did not work and the pin had disappeared. The tech apparently knew nothing about the 4 positions and just set the cam so it wouldn't turn. That made me take the machine apart and fix it myself with the other half's help. There are screws, etc, that I can't undo with bad hands.

I'll be taking the Juki into a shop I've dealt with for years for a literal cleaning. I followed the oiling schedule in posts and the manual, and there's oil all over the place. Lint, I can get.

Onebyone - My Brother is a Super Galaxie 3000 embroidery/sewing - also have a 4000. The front cover is all in one piece, with a couple of screws in the top where the cotton reel sits. Not sure about taking them out in case something inside is attached to them (bobbin winder etc as well), and no, I wouldn't want to mess with the turning wheel. They are also free-arm so taking off the bottom wouldn't help as the switch for the feed-dogs is on the free-arm.

I did see a youtube video yesterday showing how to remove the front cover, different machine though.

The 1500 is a single stitch high speed mechanical machine. It's confusing since Brother uses the number 1500 for other models just by changing the prefix. The prefix for the Brother is PQ 1500.

I am having this exact problem right now. Did you ever find a solution?

There's a bullet shaped mechanism under the machine that freezes up. It's just old oil that's built up and turned into tar. At the shop, we would just put a little WD-40 on it and work it until it lets loose. You can also apply a little heat with a blow dryer. To find the mechanism, remove the bottom of the machine. Then follow the rod that's attached to the feed-dog drop lever.