Turns out it's actually super easy, but in all the excitement I failed to take any pictures. It only took a few hours. The thread tensioner was just gummed up with fluff, and quite a few joints inside were running completely dry, so Mabel was feeling a little stiff and arthritic after 12 years of hard stitching. All she needed was a dismantle and good clean and oil.
In case you also want to join the fun and save yourself £70 excl vat and parts, here are my top tips:
- Screwdriver set (I needed big and small phillips head, and wide and narrow flat head)
- Blu-tack and pen and paper, for drawing diagrams of casework and sticking on the screws to remember what goes where
- Kitchen roll and lots of Q-tips/earbuds and toothbrush for cleaning
- Torch; ours has a magnetic pokey-thing that comes out of it which is pretty handy for locating screws
- Oil (my machine came with some)
- Suitable grease for plastic to plastic lubrication (I left these parts alone as they looked well greased anyway)
I just took the plastic parts of the bodywork off, as my Janome 423S has some metal casework which doesn't need to be removed. Then I cleaned well, removed nasty black oil, and re-oiled all of the metal moving joints, including those underneath the machine. I also cleaned the thread tensioner and bobbin race and feed dogs. Now she purrs like a contented kitten.
I found small flat-head screwdrivers useful to ease plastic lugs carefully, and I used Q-tips like nobodies business.
If you also have a Janome 423S, here's my recommended disassembly order:
- Remove the casing on the end above the needle. (The screw is hidden behind a plastic cover which can be eased off with a screwdriver.)
- Remove the plastic cover on the opposite (plug) side of the machine and remove that screw too. You won't be able to take the side off yet, so don't bother with that: you just need the wiggle room.
- Remove the plastic cover underneath the machine. There are LOADS of screws here. One of these (near the front right of the machine) you won't be able to remove through the hole: that's because it's to hold the purple front-plate on. You need to loosen this screw anyway in order to get enough movement in the front plate to work the bottom cover off. Janome have probably had to drill the hole in the casework after molding when they found you can't remove the bottom without loosening the front and side. Whoops! Once you've removed all the screws, you should be able to take the bottom off by hinging it towards the belt/motor side of the machine: you'll need to wiggle the front and side covers to get enough play to be able to hinge the plate off without snapping the lugs.
- Remove the top cover of the machine: there are screws under the handle and also one holding a bobbin-winding "stop" on. There's also one on the side at the needle-end. There's a plastic lug at the right-hand side, so like the bottom piece, the top needs to be carefully removed by hinging it toward the motor/plug side.
- Remove the side cover over the motor/plug. I didn't bother to remove the purple front-plate, as I could get the access I needed without it.
That's it, my lovelies! Service your machines now and save yourself more money for fabric!