More progress!
I wired the fans so that they now switch on when the welder is switched on and not just when it was plugged in like before. When I was re routing the wire from the fan PSU I noticed that solid 1.5mm wire that goes to the board felt loose in its spade terminal. So I soldered it in instead of just relying on a crimp.
Gave it a quick test to see if it worked and it arc'd up etc, so I made sure everything was clean and secure and built it back up again. Did a test weld on some 1.2mm scrap steel and it now works quite well on #3 and can blow holes in the metal on #4! had a bit more of a tweak with the wire speed and it seems to weld adequately on #3 albeit a little slow compared to my other machines. once the weld pool is formed, it seems to weld fine and neatly.
One thing that could have also played a part in it welding crap before was that I noticed the tip was a .8 and it was running .6 wire...... could also explain why the wire wanted to dance about all over the place too
That's a good discovery with the loose crimp. The fact that it is a sold wire means that it is likely to be one end of the transformer primary winding, probably taking the switched feed from the relay, so a poor connection there would explain the low power.
Well, I did a "thing"......... I spotted another elektrak Beckum welder for sale for spares. This time it's a Co2 160/60 Bargain at £30. Advertised as having wire feed issues.