I gave up on the tray in my masterbuilt electric. Too many times it flames up, it never produces enough smoke.
I started using a smoke tube ( made by A-MAZE-N ) and later a smoke maze (from the same guys). Fill it with pellets (any cooking pellet will work - the pit boss pellets will work fine), light it with a propane torch and put it in your smoker. It will put out a huge amount of smoke for hours (I actually light both ends of mine to get more smoke). Added a whole new life to my masterbuilt ( I have/had several pellet smokers I use as well.)
I sometimes use a smoke chief smoke generator (from Smokehouseproducts) on my masterbuilt too, when I want a LOT of smoke. I had to build an adapter for it to mate up with my masterbuilt ($3 in parts, 20 minutes to build). It is very easy to use. You put about a cup of pellets in it, plug it in, and it puts out an incredible amount of smoke. Works for cold smoking too (heat stays outside the smoker). Be sure to leave all the vents open to let out the huge amount of smoke or you will get bitter flavors. Only reason I don't use the chief all the time is that (a) it requires attention every 15 minutes (to push down the pellets-no real effort, but has to be done) and (b) it is a pain to clean the creosote out of the output tube/adapter. I am serious about the amount of smoke. I only need to smoke butts about 2-3 hours.
So, the maze is far easier, the chief puts out huge smoke but require attention.