Well, remember one side will turn one way on the star adjuster, as in up, the opposite side will be down. You will have to figure out which way one side goes, other side will be opposite. Drum brakes wear in an arch pattern so yes you might need to make more than a couple turns of the star adjuster. Your starting in the right place, the adjusters. Electric drum brakes are not "cutting edge" they are more like electric dumb brakes, except when they are new or fairly new. Once the shoes get arched life is down hill for them. If adjusting does not provide you with some decent braking power, back off the star adjusters and pull the drums and have a look at the shoes, see if they no longer have the proper shape= round/half moon, same as the drum, should be plain a day if they are worn out of shape. They do not have to have the braking pad material completely worn, just out of the proper shape, that's enough to make them not have enough contact with the drum to have reduced braking power.
eta; If your brakes sometimes work fine, and sometimes don't? your looking at an electrical problem, would probably test controller, I would just buy new magnets and install, if its not the magnet you have some spare parts, the magnets will go bad someday! What model brake controller do you have.
What kind of trailer plug do you use, flat 4 prong, or 7 pin round, those are the only two commonly use plugs these days.
