Dimplex Optimyst Problem

I am posting this because I am having problems which seem slightly different from all other Optimyst problems I've read about here

My Fire is a 10-year-old Charlotte CRT20BR and has the blue tank and grey sump, and it is only ever used for the visual effect, never for heating. In all those years the fire has perfermed faultlessly, until very recently. Here's what's started happening:

When I switch-on the fire effect I hear a bleep and the lights illuminate. 30 seconds later mist appears and makes a great job of imitating a real fire . . . so far, so good!

Then, between 5 and 15 minutes later, I hear a beep, the lights go out and the mist production ceases. If I leave the fire in this conditon it will somehow re-set itself after between 10 and 15 minutes, turning-on lights and mist to resume its normal, and very satisfactory, operation. This "start, stop, re-start" cycle continues for as long as the fire is left turned-on

Additionally: I have cleaned the transducer disc, although it didin't appear to need this . . . and it made no difference; I replaced the disc with same number (RM 0202) discs but these did not produce any mist at all (tried all three supplied with the same non-result). Replacing the original disc resulted in the return of sporadic mist, as stated earlier

I have cleaned the whole unit including fan's filter; checked that the fan runs (it draws a piece of paper towards the inlet); discovered that the lamp holders need replacing as they, and the ends of the cables, are crumbling (replacements have been ordered, but in the meantime I have ensured that there are no "shorts" at the lamp holders)

Also, I have removed all 4 lights and switched-on the fire. This makes no difference to the problem as the fire still produces mist for 5 to 15 minutes and then closes-down, and it still re-starts itself, after 10 to 15 minutes. I'm thinking that this may illiminate the possibility that the lights are activating a heat-operated cut-out device (but of course I'm only guessing and could easily be wrong)

Any advice would be greatly appreciated

Thanks for reading,
Tony

Update: I have now stripped the fire down to check for burned connections . . . and found none. I have also exchanged the crubling bulb-holders for better quality ones - but the problem persists

The symptoms point to a sensor on the PCB having become faulty - although I have no way to check this

Dimplex advise that they can send a techy to fix the problem, no matter what is entailed, for £155 all-in. But as I could purchase a complete replacement fire (admittedly not a Dimplex Optimyst) for less than this I am not keen to go this route

What I am considering doing though is building a replacement system using easily futureand cheaply available individual components. After drawing-up a wiring diagram it would seem to be the best solution to the situation, the cost of doing which would be around £50. Another advantage of doing this would be that future trouble-shooting ought to be a much simpler exercise

Comments?

Problem solved....I bought an £8 transducer from China, increased the depth of water in the sump, drilled the sump to provide an exit route for the transduvcer's cable, hard wired the transducer's mains adapter into a switched part of the fire's loom. The fire now works perfectly and performs better than it did when it was new. Very happy