There is an intermediate adapter between the tank and the battery unit (mod?)
The coil screws into the adapter, then the tank screw onto the same piece over the top of the coil.; and the whole assembly attaches to the mod.
The problem is, with that adapter in place, even without the coil, the bit at the top of the mod (with the 4 slots) is complete obscured
and there is a lip inside the adapter that bears down on the lip seen just above the thread on the mod.
I guess I could hacksaw the top off the adapter, but I’d rather work out what thread it is and put a matching thread in a piece of bar that I could then put in a vice.
The thread measures 12mm diameter, and my best estimate of the pitch is 0.75mm. Such a thread is defined in the iso standard, but the preferred pitches for M12 thread is 1.75/1.25mm, so no standard nut or tap is going to work. Then again, it could equally well be some weird BSP pipe thread.
Looking at the tank assembly on Amazon, they look very similar to these which are described as having a “510” thread; which despite nearly 50 years as an engineer, I’d never heard of.
Turns out (as many here will probably know), that means 10 turns of a 0.5mm pitch thread, which is a bloody weird way to desinate a thread. Anyhow, that turn out to be referring to the 7mm dia thread on the coil inside. (M7x0.5 also unheard of in engineering circles.)
Researching “510” threads, I came across this image:
Which led me to this explanation:
All of which leaves me with the strong feeling that I shouldn’t bother with attempting to disassemble the thing. Just bin it recycle it and move on.
Which briings me to: As you appear to be a regular here; where is the best place to ask about what I should buy as a replacement?