Singer 411G stitching issues

I bought this machine on the price alone, and thought I'd start by cleaning it. After cleaning it wasn't stitching well, so I assumed (correctly) that something I did had caused it to go out of balance.

The 411G has gold accents

The symptoms were that threads were nesting badly in the bobbin area. After perusing the 401 service manual thanks to Sewing Dude (https://sewingdude.files.wordpress.com/2012/09/singer-401-service-manual1.pdf page 131), I decided to go through and check the clearances for the bobbin case (which seemed very loose even before I cleaned it) and anything else in the bobbin area.

So this is the procedure:

Remove the needle, remove the presser foot, slide the slide plate (1) back, lift and remove the stitch plate (2).

If you want to (it's not necessary) you can also remove the slide plate. It's just like the 66 and 99. Put down the platform that holds the stitch plate then slide the plate back until it clears the spring.

You should now see this (without the arrows of course)

You will need a set of narrow feeler gauges to check the clearance. If you don't have any, you'll need to get some or guess the gap.

Narrow feeler gauges

Using the picture with the arrows, check the gap marked 1. It should be 12-14 thousandths of an inch (thou). If it's not in that range, go on to check 2, the vertical clearance between the hook and the spring, 16-18 thou. These are both adjusted at the same time, by loosening the two screws marked by thick white arrows and moving it until the clearance is right, then re-tighten the screws.

Once you've done this, check 3, the distance between the bobbin case and the spring. If this is not between 12 and 14 thou, adjust it. The adjustment is easy, but you first need to remove the machine's plastic base (two screws), exposing the locking screw (see picture below).

lock screw for adjusting bobbin case clearance

Once you've loosened it, you can turn the screw to the right of the bobbin spring (see below) which is eccentric and will increase or decrease the gap. 

Once this clearance is right, perform a test sew. My machine was made to sew at full speed with a very narrow stitch length and making a pattern, the ultimate test. It didn't skip any stitches or even hint of bunching up. Machines like this that do everything are a lot more complex than, say, a 15 or 201 so they need more attention and are harder to get to, but with the right resources (mostly just knowledge) you can keep them in top condition. 

Another problem was varying speed during sewing. This means that the foot controller's carbon pile needs a clean. This is a horrible job, so I replaced the controller. Later on I pulled out a Japanese electronic controller I've had for a few years and that was even better, because apparently you can leave these plugged in without any heating (the 411's controller was also quite hot when I changed it). The electronic replacement required a little soldering.

It's now almost perfect. The last job is to see why the motor is noisy. A drop of tri-flow was suggested on another blog, but it hasn't quietened it, so I'm thinking I'll have to remove and disassemble. Not a job I'm looking forward to, since it's completely enclosed, but I'll do it and let you know of any obstacles.

Elna Lotus ZZ

I bought this a few months back. She said it sounded a bit like a thrashing machine but confident that I could fix it anyway I took it home.

Okay it really, really sounded like a thrashing machine. The reason was the rubber drive roller (also called friction wheel).
I looked for a replacement but they're all extremely expensive. Ridiculous for such a small and unsophisticated component. Cheapest I found was $A80.00 posted from the U.S. but I can't afford that, especially when the machine cost a lot less.
The problem with the rubber is that when people let their machines run dry (of oil) which they generally do, the motor is trying to turn the hand wheel (which won't move) so it spins without moving the machine, putting the rubber roller out of shape and wearing in one spot. I suspect it's also because the rubber simply hardens over time. This is also probably more likely where I now live, in sub-tropical Queensland.
After calculating about $AU150 for a replacement it occurred to me today that the rubber feet I bought for my 411G looked about the same shape.

original Elna rubber is the black one

Do they look the same size? They're almost identical! The biggest difference is that the rubber feet are brown and had no hole. A minute later one of the brown feet had an appropriately sized hole (careful with the drill, I had to hold it with my fingers) and after another minute and it was in the machine, which is now as quiet as a mouse. I hadn't heard one before so didn't realise how they should sound. It's really a pretty nice machine that stitches well. It's portable like the featherweight, but can make a zig-zag stitch.

I pushed the new roller on and replaced everything

Tell everyone you know who might have one of these, since it's a very common issue. With a one dollar part you can fix this problem really quickly.
The original only lasted 30 before giving trouble, so even if your replacement lasts only a year, I'll still be $50 better off, assuming I'm still around in 30 years.