Lists two different stators depending on serial number. It looks like replacements are available. It also looks like there is no regulator, just a diode. This means there is a limit to the current that it puts out, probably 3A or 5A.
Here is something to think about on your PTO coil resistance. At 3 Ohm and 12V it will draw 4A. If your stator only outputs 3A that will drain your battery. The other thing is that the output is half wave rectified, so your measurement of the current is likely incorrect (since half the time there is no current provided, ie blocked by the diode). I would also question the measurement of the coil resistance. Accurate low value resistance measurements require very expensive equipment. The error rate of low cost equipment is very high. My expensive Fluke meter does a poor job. It has an offset of 3ish ohms and even if I subtract that it's error percentage is VERY poor until above 10-20 ohm.
I would measure the current draw of the PTO. That is likely to be reasonably accurate, even with a cheap meter.