Have worked through several mystery battery drains in 240s, I'll share the most common one. The delay relay for the interior dome light (some will delay and then gradually dim the light), mounted just above the brake pedal, small black cylinder. I've had them cause drains... I guess they get stuck and don't completely turn off. Simply disconnect the wire, the dome light still works, just no more delay. Took me a year to find this the first time because the drain was intermittent and so small I couldn't detect it. Now it's the first thing I check when I find a drain... turns out to be this almost every time.
Dave B