Most of the HGM lasers I've bought in the past worked fine, but had high pressure tubes that needed to be burned in to get them on an even keel. I found that using a rectified and current limited microwave oven transformer works the best for getting them in a condition to be able to start reliably. Once you get it to start, run it for 48 hours or so and it will be good as new. The draw back is they are power hungry, heavy, fragile, noisy, and make a LOT OF HEAT.
In fact i even used one as a space heater when the temps up here in Wisconsin got into the negatives, kept the tube in tip top shape, for heating these are a lot more efficient than your average space heater watt for watt..