Okay, you are in the UK, and it's winter. So I'm assuming that you are diving in pretty cold water. It sounds to me like you had a freeze-up situation develop, and servicing the regulator won't change that. It will happen again under similar circumstances. It sounds like your regulator was doing fine until it started free-flowing at 33 meters (about 108 feet depth).
Please look over this publication by Dive Lab about regulator freeze-up. Here is part of what they say in this report:
2.5 Regulator Freezing in 50°F (10°C) Water: So how does ice form in the second stage if you are not diving in water much colder than 50°F (10°C)? Simple! When the high pressure air passes through the first stage regulator, the rapid drop from high pressure to low pressure causes a dramatic temperature drop. This pressure drop is basically how your refrigerator and air conditioner work, the temperature drop is fairly linear, the higher HP pressure the greater the drop in pressure and the colder the air gets at the second stage. Now increase the flow and it gets even colder. If you can keep your breathing rate at the low to moderate breathing rates (15 - 30 lpm flow) the risk of ice formation is less and you will minimize the potential for second stage freezing. See: Table 4 page 16. The temperature / breathing tables show how extreme the cooling can get.
https://divelab.com/download/proced...ubaRegulatorFreezing-ChillingFacts-4-9-14.pdf
So take a look at this and see whether it matches what happened to your Aqualung Titan. That regulator is a great regulator, with great breathing characteristics, but those very characteristics can influence the temperature change in the second stage, and make ice formation happen more easily.
The depth can affect this freeze-up situation, as more volume of air is passed through the valve. Remember the universal law:
P1V1/T1 = P1V2/T2 (the temperature is not degrees C or F, but rather degrees K or R.
If you flow a greater volume of air, it will affect the temperature.
There is another thread here on Scubaboard which discuss this. Here's one post:
JimmyC: Rivers, Aqualung North America recommends you not use it in water colder than 50 degrees as it may freeze up. If it is an LX it will have the ribbed heat exchanger on the 2nd stage. It would help you out to install the Enviro kit as mentioned as it will give you a better edge against the cold.
Question about Aqualung Titan and water temperature
What exactly does the little adjuster do on a second stage and what is the ideal position for it? Cheers
That knob will allow you to adjust the spring tension on the second stage valve, thus increasing ore decreasing the effort required to open the valve. Screwing it in increases effort, and screwing it out can decrease that effort to the point where it will leak air a bit. But this would not affect the process by which a regulator second stage freezes.
SeaRat