my presto pressure canner won't come up to pressure, the weight just jiggles a little steam but the gauge never moves past zero

Diagnosis

The failure of the Presto 01781 to reach pressure, characterized by a "jiggling" weight and a stationary gauge, indicates a critical failure in the vessel's airtight seal. For a pressure canner to function, the internal steam pressure must exceed the weight of the pressure regulator (the weight). When steam escapes from a secondary source—such as a degraded gasket or a faulty valve—it prevents the internal atmosphere from reaching the 10–15 PSI required to move the gauge or lift the weight fully. This is most commonly caused by a "blow-by" at the rim of the lid or a leak through the overpressure plug. If the rubber gasket has developed a microscopic tear, become brittle from heat, or is improperly seated in the lid channel, steam will bypass the regulator entirely. You can confirm this by observing the lid's edge during the heating phase; if you see wisps of steam escaping from the perimeter of the lid rather than exclusively through the vent pipe, the seal is compromised. Additionally, if the gauge remains at zero while the weight is dancing, it confirms that the pressure is venting at a lower threshold than the gauge's minimum sensitivity.

How to Fix It

To restore the airtight seal and ensure the unit reaches the proper canning pressure, follow these precise steps:

1. Allow the unit to cool completely and ensure the internal pressure is zero before attempting to open the lid.
2. Remove the lid and locate the large, circular rubber gasket seated in the rim channel. Pull it out and inspect it for any cracks, thinning, or "flat spots" where the rubber has lost its elasticity.
3. Thoroughly clean the lid's gasket channel using a damp cloth and mild soap to remove any dried food particles or mineral deposits that could prevent a flush seal.
4. Inspect the overpressure plug (the small rubber vent in the lid). If it appears cracked or shifted, pull it out and re-seat it firmly.
5. Apply a very thin film of food-grade mineral oil to the new or cleaned gasket. This helps the rubber seat more effectively against the aluminum rim.
6. Place the gasket back into the channel, ensuring it lies perfectly flat without any twists or overlaps.
7. Lock the lid using the clamps, ensuring the tension is even across all points. Over-tightening can actually warp the seal, so tighten until snug but not strained.
8. Fill the canner with the required amount of water (usually 2-3 inches) and bring it to a boil before placing the weight on the vent pipe.

If That Didn't Work

• Replace the Gasket: If the rubber is more than two years old, it has likely lost its structural integrity. Order a genuine Presto replacement gasket specifically for the 23-quart model. Generic gaskets often have slight diameter variances that lead to the exact "zero gauge" problem you are experiencing.
• Inspect the Vent Pipe: Use a pipe cleaner or a thin wire to ensure the vent pipe (where the weight sits) is completely clear of debris. If the pipe is partially clogged, the weight may jiggle erratically, but the pressure will not stabilize correctly, often leading to erratic gauge readings.
• Test the Pressure Gauge: If the lid is sealing perfectly (no steam leaks) and the weight is lifting, but the gauge stays at zero, the gauge itself may be faulty. Compare the gauge's behavior to the weight; if the weight is steadily steaming but the needle doesn't move, the internal bourdon tube of the gauge has likely failed and the gauge must be replaced.
• Check the Rim for Dents: Run your finger along the top edge of the canner body. A small dent or scratch in the aluminum rim can create a gap that allows steam to escape, regardless of how new the gasket is. If a dent is found, you can sometimes lightly sand it smooth with a fine-grit emery cloth.

Heads Up

• Never use a screwdriver or knife to pry the gasket out of the lid, as this can scratch the aluminum channel and create permanent leak points.
• Always perform a "dry run" test with water only when replacing gaskets to ensure the gauge reaches the target pressure before adding food jars.
• Avoid overfilling the canner; leaving too little headspace can cause liquid to be pushed into the vent pipe, causing the weight to stick or the gauge to read incorrectly.
• Store the canner with the lid slightly ajar when not in use to prevent the gasket from compressing permanently against the rim.