If it is the original style 3 terminal switch it could be the problem. The originals are old and probably well past their life expectancy. If a replacement, some of the more modern replacement switches that have been used have not had great reports for longevity.
I would suggest you order the brake switch conversion kit from the Pacific Northwest region which will replace the original style switch with a modern 2 terminal switch and a relay to duplicate the function of the third terminal. Here is a photo of the conversion kit.
https://packardinfo.com/xoops/html/modules/newbb/viewtopic.php?post_id=213872#forumpost213872 Kanter and Max may also sell the hydraulic conversion kits and Dwight Heinmuller also sells a mechanical kit which totally gets rid of the hydraulic switch. Many of us have gone that route.
https://www.packardparts.org/products/parts/#prettyPhoto The torsion level control switch gets its power thru the brake switch and if the brake switch is faulty and staying on to keep the brake lights active it would definitely affect the level circuitry and could be the cause of intermittent operation.
Assuming you have power brakes (and manual too but a lesser chance), there is also a possibility the brake pedal is not coming to the normal resting position when you remove your foot. If that is the case the fluid in the master could be trapped and unable to get back into the reservoir. With heat the fluid will expand and that pressure might be keeping the switch on. The next time it happens, before disconnecting the battery you might reach down and pull the pedal back with your hand to see if that makes the switch go off.
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