I recently repaired a crack and a chip from one corner of my CPA2 top cover using fiber glass sheet and resin. I repaired it on the underside and then sanded the repair flush on the front side, resprayed it with a red paint and sealed it all with clear lacquer and it looks like new. I think a resin or epoxy glue on its own won't add much strength to the repair and may crack again. I am almost tempted to cover all the underside of the tray as it makes it so much stronger as they are very flimsy as standard.
I have also used these materials to fabricate an unusual shaped shore for my gutter drains and it works perfectly with no leaks so water is not an issue.
Thanks again to all for your tips. Went to the hardware store and asked them for some Goop. Cashier said he didn't have any. He kept blowing his nose a lot. Empirically that could support either of the Goop/booger chicken or the egg theories. Not wanting to probe further, I asked him if he had JB Weld. He did and my CPE-2 is now nicely slathered and curing. Hopefully tomorrow it won't look like a sieve in action. Firestarter, I think your method is the most comprehensive but, as I am generally lazy and unmotivated, the Goop/Weld options prevailed.
"There is a time and place for all things, the difficulty is to use them only in their proper time and places." -- Robert Henri
I would recommend a urethane based product because it sticks to anything and it remains flexible when it dries (like your Jobo processor). McNett Corporation makes a number of variants, such as "SeamGrip" (used to repair wetsuits and tents) and "Freesole" (used to repair running shoes). They are generally sold in sports stores.
For hairline cracks in the Jobo processors and the drums my first choice is a liquid plastic cement of the type used for model aircraft. This is the sort that comes in a bottle and is brushed on, rather than in a tube. The advantage is that it will get drawn into the crack by capillary action and "weld" it shut. They aren't any good for larger gaps since they don't add any new material. The "Testors" plastic cement I use is actually Methyl Ethyl Ketone, while when I was in high school we used Methyl Methacrylate for the same purpose.
The advantage of using epoxy like West System, Systems Three, MAS or other brand is that epoxy will flex even though it will hard cure. The 5 minute types have even greater flex but the bond is not quite as structural. Other resins, such as poly based are very brittle when cured. They are a wide range of DIY type epoxies hanging on hooks in stores. These simple epoxies can vary greatly in bond strength on various substrates. Surface preparation is very important no matter what you use. Products like Goop and other standard household adhesives should not be used if you desire a long duration quality repair. Another factor is that epoxies are gap filling adhesives, whereas many standard adhesives are not.