DIAGNOSIS Your dial gauge is stuck or damaged. It's a mechanical device with a small Bourdon tube inside that can get clogged with minerals or simply fail over time. If it doesn't return to zero when cold, it cannot give you a reliable reading during processing.
FIX Do not rely on a faulty gauge for canning. Your safe options are: 1) Use the three-piece regulator weight alone. When it's rocking steadily (about 1-4 times per minute), you're at the correct pressure (which is 10 PSI for that weight setting). Ignore the stuck gauge. 2) Contact Presto or a local county extension office—many offer free gauge testing and can tell you if it's repairable. 3) Order a replacement gauge from Presto's parts website. They are designed to be user-replaceable.
IF THAT DIDN'T WORK If you're uncomfortable canning without a gauge, you can send the entire lid to Presto for service. They can replace the gauge and check the other safety components.
HEADS UP For safe canning of low-acid foods like vegetables and meats, accurate pressure is non-negotiable. Always have your gauge checked at the start of each canning season, even if it seems fine. A stuck gauge is a clear sign it's time for service or replacement.