Identify vintage capacitor

Question

What is this component? Words on it say something like:

  DUIULER
0.1 ? +- 23%
250V 50~ WKG
    TL

Where the "?" is a literal blob of ink that could be anything.

In circuit it lies across the phase and neutral lines, in parallel with an enormous chonking ceramic horizontal rheostat-like resistor-thing. (edit turns out it is a carbon pile resistor in two stacks, with a ceramic housing.)

The outer surface is slightly tacky, but that might be the kapton-like tape around it.

When measured, it returns a value of 15.80 microfarads, but take that with salt.

In situ it looks like this:

Background

I have a 1957 Singer 201K sewing machine that has had a motor kit retrofitted. It has worked well for decades, but in the last few years the pedal started getting hot, and it once started sewing all by itself.

Web searches suggest this is a

• Noise supression capacitor and is redundant in the modern world without AM radio, can be safely removed.
• Smoothing capacitor, again redundant given its not the 1950s any more.
• It might also be a snubber to help protect the resistor-block.

Links:

1. Example of site saying to simply cut it out.

2. Video showing how to clean the carbon pile resister.

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Results: I have deleted the capacitor, and the sewing machine runs perfectly without it.

I've also cleaned the contents of the ceramic carbon pile resistor, and that was very dusty and dirty. There's over a hundred carbon disks inside it, of which ~5 were broken. Cleaning all the carbon off brass contacts has also helped enormously, and the pedal does not get as hot. I also am running the pedal on a scrap of wood, not on the carpet.

Answer 1

It's an old film noise suppressor cap

What you have there is a quite old noise suppressor cap, made from metallized film or film and foil. The correct replacement for a cap like this is not a 400VDC cap of any type though, but an X-rated safety cap with the same value and a safe working voltage rating of at least 250VAC (note that the rating on X and Y caps is in volts AC!!). These will universally be film type capacitors, and are tested so that they do not create a hazardous failure potential when connected across the mains (line-to-neutral).

Answer 2

The markings appear to be:

DUBILIER
0.1 µF ±25%
[2]50V 50~WKG
TL

You should be able to replace it with an axial non-polarized 0.1 µF capacitor rated at 250 V (or higher) with a tolerance of ±25% or better.

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Edit: As noted in the comments this is a 250 V part, not a 50 V part. This value is appropriate for a 120 VAC supply but for 240 VAC use you should choose a part rated to at least 400 V.

Answer 3

As you look to replace the capacitor, you should also look at the splices in your mains wiring per high lighted cropped photo below. And, your contacts appear to be bent (just in front of the cap in your photo.