Repair 12/24V PIR.

I have one of these that does not switch off . I have 6 that the timer is set to 2 minutes minimum setting . I want to bring it down to 30 seconds.
Does anybody know or can guess at the circuit?. The variable resistance is 204 which I think is 200KOhms . I tried substituting a 104 ,100 Ohm pot but it did not work.

They work great with 24V until they just stick on which was after a month and some thorough drenchings

Does not look like anyone uses them yet . They are all over ebay and generally work well . I'd like to get a circuit on them !