The degrader 1.3 should help you a lot. (1.0 was really not intended to run on an AGA machine!) (I'm assuming the problem is that you have the degrader on your PC, and are having trouble getting it to the Amiga? If all else fails, perhaps a null-modem connection and an X-modem file transfer can help?)
For using degrader on many games, I use the options "Privledged, NoCache, NoView" and "Survive Resets" to reboot the machine. Sometimes it hangs my A1200, but the three-key salute resets it, and it cycles through a couple additional colors before booting up again. (This is good, as you know degrader "took".)
The typical problems that "NoView" fixes are graphical glitches. Often times it will be a screen that looks like it has been horizontally "smeared". The "NoCache" will fix certain gurus, and sometimes fix screen flashing.
And, "Privledged" usually fixes the 8000 0004 or 8000 000B gurus.
Also, another program I use is "TUDE" available from Aminet, along with a 1.3 ROM image. between these two programs and various options in each, I've gotten most everything from my 500 collection to work on the 1200. Certain titles cause more problems than others, of course. (my original to Shadow of the Beast was horrible until I found a WHDLoad for it!)