AGB I yield totally to Don on this question. I had some basic Latin in high school and college, but never had the first class in Greek.
I still hold out the hope of making some progress in understanding some basic Greek, but I decided some years ago that devoting a lot of time to basic Greek would not be the best use of my time. Perseus, such as Don suggests, and the side-by-side translations let us do basic honesty-checking, but it seems to me that when classical scholars who devote their whole lives to studying the minutia can come to such different conclusions, any hope I have of being able to second-guess them is itself minute. No doubt there is a lot of pleasure in being able to grasp the original (as I can do somewhat with Lucetius) but in the end the subtleties of the philosophy are going to turn on connotations of words that will always be obscure to me. In those cases, like with an expert witness, I think it's best for me to yield to those who have invested the time to study the known usages of those words in detail.
For that reason I've made a point of always checking three or four (or a many as I can get) translations against each other for consistency, but in the end I go with the one that seems to me to have the best grasp of what I think Epicurus was intending to say -- with the standard being the direction that the whole philosophy seems to be pointing. Whenever a translator comes up with a version that seems to point in a different direction, that sends up the red flags that I try to heed.
For that reason I often listen to DeWitt's versions over some of the others, and in Lucretius I prefer Munro over Bailey, and even the 1743 version over some of the later ones. I think DeWitt, Munro, and 1743 have the most "sympathy" with Epicurus' philosophy and are less likely to go off-key than Bailey.
Again as to Lucretius I also stay away from the "poetic" translations to the extent possible, although I do think Rolfe Humphries has an inspired choice of words in many cases.
There definitely are a number of passages that are either mangled or so foreign to us that we don't have a clear idea of their meaning, and so lend themselves to controversies. I put the whole issue of "absence of pain" near the top of that. I certainly see how sections of the Letter to Menoeceus, and some other passages, can be read to point in one direction, but I also firmly think that the great weight of the philosophy points in a direction different than many modern commentators would give to those selections.
So you may be retired, but it's not time to put away your "statutory interpretation" skills because they will definitely be needed in "reconstructing" many important questions.