I purchased a closeout Rival Crockpot. It is model 3122 CH & has a 2 QT capacity. It only has 2 settings...on/off. Is the on setting high? And.. what is the actual temperature of "ON"?

No parts exist. It is a make without a maker.

https://www.google.com/search?q=tru+model+bs-41525+replacement+parts

Crockpot (the brand leader) parts do exist.

https://www.ereplacementparts.com/search_result.php?q=crockpot+lid

You might be able to use one of these and swap the chrome ring from the old one?

crockpot replacement lids - Amazon.com

https://www.amazon.com > crockpot-replacement-lids
Results 1 - 48 of 1000+ - Amazon.com: crockpot replacement lids. ... Compatible Round Glass Lid for Rival Crock Pot & Slow Cooker 5 6 Qt SCRC507-W.

Crock Pot Replacement Lids - Walmart

https://www.walmart.com > crock-pot-replacement-lids
Crock Pot Replacement Lids ; Rival 7 Quart Crock Pot /Slow Cooker Replacement Oval Glass Lid · $22.51. current price $22.51 · 104.3 out of 5 Stars. 10 reviews.

YPD Replacement Oval Glass Lid Crock Pot & Slow Cooker ...

https://www.amazon.ca > Replacement-Glass-Crock-Co...
Oval in Shape; Replacement Glass Crock Pot Lid For Rival 5 1/2 to 6 Quart Crock Pots And Slow Cookers; Glass Lid with White Plastic Knob; Measures: 12 1/4" ...
Rating: 4.4 · ‎89 reviews

Glass Crock Pot Lid ' Etsy Canada

https://www.etsy.com > market > glass_crock_pot_lid
Check out our glass crock pot lid selection for the very best in unique or custom, handmade pieces from our shops. ..

All the info I have seen for this model indicates that the setting dial is "Off" when pointing at about 10 o'clock position and then "Low" is at 12 o'clock and "High" is at 2 o'clock. No numbers like 1 and 2 are used.
I would assume if your dial is laid out the same way that it goes from Off to 1 to 2 ... then 1 would be Low and 2 is High

That is 1970's.

Here is a great copy of the manual for the 3150 3.5 quart crock pot that I like. http://www.megaheart.com/pdf/crockpot-cookbook.pdf

Here's a PDF with a copy of old Rival Crock Pot manual. Page 8 discusses recipe help for the 2 Quart model. http://www.megaheart.com/pdf/crockpot-cookbook.pdf

When it's plugged in, it's "on". All Rival crockpots heat up to simmer, which is about 209 degrees, and then stay there. So whether it's "Low" or High" or somewhere in between, it will heat to the 209. I got this information from the Rival web site when I was researching for information on my 1 qt. and 2 qt. crockpots that I have no manuals for. There's a manual for the 1.5 quart online but after I printed it off, I lost the URL. Go to www.crockpot.com -- maybe that will get to the manual, or at the least, it should give you a Customer Service phone number to call to request one, or directions where to find it online.

Try the hardware store. Look at the dimmer knobs.

Try one of the following sellers:

To contact the manufacturer, try calling 800 #. 1-800-323-9519 (US number) for replacement parts or try www.crockpot.com

Rival Crock Pot Replacement Parts from MarBeck.com

Crock Pot Replacement Parts | Slow Cooker ...

I am in need of a Rival Slow Cooker liner for model # 38501. If anyone knows where to buy a replacement 5 qt white liner, please respond.

I have had the same problem. Spoke to rival customer service and they no longer sell replacement lids for model number SCE502. I've read to take the screw from the knob to a hardware store and then find a knob which will fit it.
Someone else suggested that if the knob is mostly intact, ask hardware store for araldite glue