Singer 306K - Freeing up zig zag and needle position L-C-R levers, and eliminating clacking sound

I picked up this Singer 306K a little over 4 years ago. The thing actually showed up in a *free* ad! It was, however, in much need of some pretty serious attention and was missing some minor bits (one of two locking thumb screws on zig zag assembly and the stitch length stop, from what I recall). Oh, and the bobbin case lever was snapped off. Not sure how that could happen.

Be that as it may, I was still up for the challenge. Here the condition, before doing anything to it:

A pretty sorry sight. Most folks would probably send it to the dump. For someone like myself, though, it's a goldmine of intrigue. Can I get it unstuck? Can I even, dare I say, get it operational again? We shall see.

The first order of business was to get the machine whirring along as it should. That took longer than normal. Usually I can blow out the cobwebs and add oil to these dejected machines and within a few minutes they're purring along nicely. This one, however, was a different animal. And of all things, the motor was making a horrible racket. I popped off the drive belt and happened to notice the drive pulley attaching screw was halfway backed out. I tightened it up and wonder of wonders, it sounded like it should.

After maybe 20 minutes of oiling things and moving levers, the sewing machine started loosening up. But then the zig zag lever started seizing to the L-C-R needle positioning lever. Move one lever and they both move. That's not good. Sooooooo.....

I'd never taken a set of these control knobs off a machine before. These knobs are the same as on a Singer 319W (and possibly others I don't know about). To get the knob assembly out of the machine, simply loosen two set screws under the assembly (two red arrows below) and pull the whole mess out the front:

Be careful you don't lose the sliding block on the back end of the assembly. It fits into the slotted piece in the far left of the photo below.

The slotted end piece mentioned above has a screw in the end that needs to be removed plus two set screws on its side that need to be loosened to get the assembly apart. Once disassembled, it was just a matter of cleaning everything up, oiling it, and putting it back together. One thing to note, as shown below, the part on the right has a circled area where the pin in the left piece needs to fit into.

What I did was slide the spring-loaded block over a bit (see below) and tighten the front lock screw to hold the block in position. That gave enough room for the pin to fit and mate the two pieces together. The first time I tried to do it, I didn't realize the sliding block was in the way. One thing I thought was fascinating was the intricate locking mechanism used in the piece on the left. It is a brass or bronze piece with a very small block in the center part of it that a locking screw bears down on from the outside. The intricate parts Singer manufactured are quite amazing. I can see why these old machines were so expensive when new.

Ok, we're almost done. The round slotted part that fits onto the back end of the assembly needs to be clocked a certain way to have the zig zag work properly. Set the zig zag lever to "5" and hold it there.

Then push the slotted piece onto the back end of the shaft and line up the two set screws to the holes in the main body. Tighten the screws down......

... then install the screw in the middle.

Next put in the sliding block...

... and slide the assembly back into the machine, being sure the hole in the block mates with the pin (arrow):

Finally, tighten the assembly into position. During this process, set the zig zag lever to "0" and the L-C-R needle position lever to the Center position, then watch the needle and turn the whole assembly in the machine left or right in order to center the needle in the middle of the presser foot. Now tighten the two set screws. I don't know if that's the proper way to set things up, but it worked for me.

One other thing I found out of adjustment on this machine was the main shaft. When the machine was running, it would make a loud CLACK every time the zig zag cam got to the position shown below. The cam turns clockwise, and when the pin riding on the cam got to the edge of a hump, the tension on the pin was enough to rotate the cam a small amount, which then pushed the entire main shaft to the right, causing the clacking sound.

A simple fix to this is to take up the slack in the main shaft by loosening the two set screws in the collar on the left side of the main shaft, then tapping the collar to the left until all the slack is taken out. Then the two set screws are tightened again. After I did that, the machine was quiet when running. Well, maybe not whisper quiet, but as good as it gets for one of these.

And there's always the obligatory sewing test after everything is back together. I'm guessing it's been 30 years since this sewing machine has sewed anything. How satisfying is that!

Oh, about the bobbin case lever. I had another bobbin case (a lowly Class 15) laying around (doesn't everyone?), and I was able to just swap levers from one to the other. It's just a matter of removing a minuscule screw on the inside of the case and rotating the lever out to release the cam. Then the lever assembly slides out of the case (being mindful of the minuscule spring in the case). I unfortunately didn't get photos of that process.