The gauges aren't the cause of the popping problem you described.
If your oxygen line pressure climbs when the torch isn't being used,
and/or you can't keep the flame regulated while in use, then there
is a problem with the gauge - probably the oxygen regulator. Note:
your oxygen regulator line setting knob should always be backed off
each time you close the valve on the oxygen tank. After time it is
normal for the line pressure to leak down and when you reopen your
oxygen tank valve the sudden rush of the tank pressure released into
the line side of the regulator could, and will, damage the diaphragm
in the regulator.
But, the problem you describe is in the torch valves itself. It
sounds too me like you might be a bit heavy-handed in turning the
torch valves off and may have damaged the seat and/or needle of the
torch valve. Take the valves off the torch and take a look at them.
It is a simple needle and seat type valve. If you see a fairly deep
line going all the way around the needle (male), you have a damaged
valve. The way we use our torches, opening and closing the valves
many times a day, a faint to shallow line is normal, but a deep one
could be a source of a problem with the torch. Take some sandpaper
and resurface the male needle. If it's real deep, you may need
something a bit more aggressive such as a file, but it is possible.
Get the needle as smooth as you can and be careful to keep the angle
as near the same as it is originally. I've been using my Hoke for 30
years but I don't know exactly how old it truly is because I bought
it used - used to the point of some of the plating being worn off
already. I've resurfaced the needles a couple times and keep on
going. My torch has popped when I turn everything off for years.
Probably not the safest scenario, but I've never been terribly
concerned with it. The way I avoid the pop is to open the torch
valves after I shut down the tanks and release all the pressure in
the lines. I also have in-line flashback arrestors installed on each
gas and oxygen line. Something everyone should consider for safety.