If your Presto pressure canner only has a gauge, without the 3-piece weight system (sold separately), then you need to get your pressure gauge checked annually, ideally during the winter or early spring.
If you get the Presto 3 part weight, you don’t need to get your gauge checked yearly — or ever, really. The weight becomes all that you need to rely on. You leave the gauge on — but it becomes instead just an indicator to let you know when the pressure is returning close to 0 so you will be able to take the lid off.
That being said, even those who have the 3-part weight often like to be able to refer to the gauge as a rough backup mechanism. So here’s information on how to get your Presto gauge checked.
See also: General information on pressure gauge testing, including for other brands.
Presto Pressure Canner Gauge Testing
The Presto company will test your Presto pressure canner gauge for you, at no cost. You must pay the postage to them; they will pay the return postage.
The Presto Company will test dial gauges FREE! Remove the gauge from the canner lid, wrap in newspaper, and package in a small sturdy box. Send the package to: PRESTO – Service Department, 3925 North Hastings Way, Eau Claire, WI 54703-3703. The customer pays the postage to Presto. In most cases, the gauge will be returned in a short amount of time. Check with your local County Extension Office to see if there is a local source for testing…. For more information, phone Presto Customer Service: 1-800-877-0441 or email@example.com.”  https://www.extension.umn.edu/food/food-safety/preserving/canning/testing-dial-pressure-canner-gauges/ and https://www.extension.umn.edu/food/food-safety/preserving/general/food-preservation-faqs/
This information is current as of spring 2018; it was confirmed to us in writing by a Nancy Becker from Presto. She points out that the free testing, while it is still offered, may not be the best option for everyone, particularly people from Canada. She wrote,
Many county Extension offices test dial gauges as a service to their residents. In some instances where the Extension office does not provide the service a local hardware store may do so. In those situations where our customers are not able to get their dial gauges tested locally they can send them to Presto. Testing is free of charge, but the customer does need to pay postage/shipping costs to get the gauge to us.
Canada is a different situation because there is no Extension Service able to provide testing, and there is no network of hardware stores that provide the service. Sending the gauge to Presto is not a good option because of the big expense and time factor involved. So we encourage our Canadian customers to get a 3-piece pressure regulator.” Nancy Becker of Presto to Randal Oulton. 5 February 2018. Email on file.
The advice to Canadians would apply equally to those in other countries as well — just factor the cost of the 3-piece weight in when you are planning your initial purchase.
Presto Pressure Canner Gauge Testing Tool
Presto does sell a gauge testing tool, but they won’t sell it to individuals, only organizations. The reason apparently is that qualified training on how to use it is required.
Here is the order form for the Presto Dial Gauge Testing tool.
Demonstration video for gauge testing tool
The following demonstration video was made by Dr Sandra Bastin, for the Cooperative Extension Service at the University of Kentucky.