Are you sure they can't be adjusted some more??

  Should be some info on the trailers serial number plate as to what weight/size axles you have. There should be a data plate on the axle itself giving you the make model and serial #.. Best way to know for sure is to pull a drum and measure the shoe size...... That means the trailer will be down until you get the parts or you'll have to put it all back together until the parts arrive. Save some time and money by replacing the whole backing plate along with the magnets, springs, and shoes, four bolts and two wires and you're ready to go!!... be sure to install new grease seals, your new brakes are only as good as the grease seals. Some examples below..

http://i.b5z.net/i/u/1080235/f/parts_kit_cat_8-08/Complete_Brake_Assemblies.pdf

http://www.redneck-trailer.com/2009/C/C11-C13.pdf

You can also learn the axle capacity of the Exiss by the data plate on the top left hand side of the hitch's down tube. Once that is learned, the brake assemblies are fairly standardized depending on the axle's weight capacities.

Here's one source: http://www.easternmarine.com/em_store/trailerbrakes/trailerbrakes_ele.html