I bought a meat slicer with an improperly replaced potentiometer that controls the speed of the automatic function. I found the proper part and have attached an image, but the part is not available to buy. I would like to create a circuit that permanently sets the speed to about the half-way point of the potentiometer. How would I do this?

 

You use two resistors with the sum of their resistances equal to the total pot resistance (two equal value resistors should give about half speed, but you may need to tweak the two values to get the desired speed).
You connect the two resistors in series between the two connections where the pot outer terminals were connected.
The junction of the two resistors goes to where the middle terminal (wiper) of the pot was connected.

 

The attached photos are not of a potentiometer, but of a 2 pole 6 way switch, where 3 of the ‘ways’ are not used/connected.

I suspect that besides controlling the speed (dependent on the switch position) it is also acting as an on/off control.
Replacing it with a bespoke part, to do what you want, might be a bit more complicated than altering a resistance value.

 

If it helps, the resistor values in the photo are:-

R1 = 180kΩ
R2 = 75kΩ
R3 = 26kΩ
R4 = 15kΩ

Since it is easier to add a resistor in parallel, I suggest you half one of the values by soldering the same value in parallel and see what effect it has – or alternatively replace the resistor completely.
You might be able to replace a resistor with a small potentiometer to allow fine adjustment to achieve the desired effect.

 

If it helps, the resistor values in the photo are:-

R1 = 180kΩ
R2 = 75kΩ
R3 = 26kΩ
R4 = 15kΩ

Since it is easier to add a resistor in parallel, I suggest you half one of the values by soldering the same value in parallel and see what effect it has – or alternatively replace the resistor completely.
You might be able to replace a resistor with a small potentiometer to allow fine adjustment to achieve the desired effect.

The switch was replaced with a potentiometer that was toast when I got it. What if I just wire in a single resistor and have a single-speed machine? Then could I just up/downgrade the resistor to find a speed that works for me?

 

Yes, you could try that, but remember that a pot has 3 connections with a centre wiper. If there are only 2 connections (to the pot) and you have a selection of resistors, I’d start with the highest value and work down.

 

looks like there are only two spade terminals (J1/J2). so the entire circuit is acting as single resistor. it is unclear what the proper connections really are and what range of values was originally possible. maybe it could be open circuit, closed circuit and set of value in between. but i would dare a guess that using 250k potentiometer (or trimpot) will give you plenty of adjustment. may want to add 10k fixed resistor in series with it. and perhaps pick one for 1 or 2W of power since current/voltage is not known.

example
https://www.mouser.com/ProductDetail/Bourns/93R1A-R22-A22L?qs=iuQ%2BhjgTeii9Q0P3UWxVLw==

 

Thank you all for your help