De-gassify a liquid filled compass

Most liquid capsules will develop bubbles over time. This is especially the case when they are brought from low and warm to high and cold altitudes and then back down (or any major elevation change and return). Just leave it in the sun and it will mostly (of not completely) return to normal. You can run small bubbles in a compass, almost a help to assure proper level - but they are annoying and can inhibit operation if they get too big.