It turns out my bottle was stamped with two weights, full @ 190 and empty @ 115. When I had it inspected, it weighed 187, which I am told is therefore in compliance. To be in compliance, a bottle must be within 10% of the full charge, which allows for a difference of 7.5 lbs (10% of the 75 lbs of CO2). Therefore, anything above 182.5 lbs is good to go.
Even though the bottle was good, I had a problem with the firing mechanism. It wouldn't trigger the firing pin, manually or by heating the biscuits. Finding out replacements are no longer available, I decided to tear the unit apart and see if it could be fixed. (The fire service company claimed it couldn't be rebuilt). By the way, I have a unit manufactured by Norris Industries. Anyway, it turns out that a bracket located in the guts of the unit was bent, most likely from someone trying to reset the unit by turning the knob in the wrong direction (clockwise, the wrong way, instead of counterclockwise). After straightening the bracket and reassembling, everything worked perfectly (manually and by heating up the biscuits).