The Italamec flasher unit is load sensitive and prone to degredation. As far as I am aware the load is calibrated for total wattage draw and so you just can't use any 5 pin load sensing flasher. In order to get the lights flashing at the correct rate then you need a like-for-like spec of flasher unit...which is difficult to determine / source.
However, the good news is that the load sensing flasher (LSF) is intended to be able to identify when a bulb has blown in which case the lights flash raplidly to indiacte this. If you are not bothered about this function then you can use a 2 pin NON load sensing flasher which are as cheap as chips and will flash at a steady rate regardless.
This may help you temporarily with your problem determination to introduce a cheap non load sensing flasher to ensure the rest of the flasher circuitry is OK.I did exactly this and introduced a standard Narva 2 pin flasher with a wiring shunt for the handbrake warning light whilst I was able to source a replacement for the Italmec. I thought a 3 pin relay may have been necessary to also send a signal to the dash indicator tell-tale but seemingly not as mine work fine with a 2 pin flasher.
I have since introduced LED indicator bulbs and therefore left the Narva 2-pin flasher in place as LED's simply won't work with the LS type. (would have had to introduce resistors to compensate for the low power LEDs and that seemed like too much hassle).
Anyway, this was how I tackled it as I didn't want to be held to ransome for a replacement Italmec.
Cheers,
Steve
PS. I am aware that the ITALMEC unit also flashes the handbrake warning light. However, mine now just lights but doesn't flash....but I can live with that or I could just introduce a second 2 pin flasher instead of the wire shunt
