This is what I discovered about denatured alcohol so far:

"There are many forms of denatured alcohol. In addition to alcohol (methyl, ethyl, and/or isopropyl), some contain (for example) ethyl acetate; some contain methyl ethyl ketone. The ethanol/methanol mix may be appropriate; these others may not be. "

The stuff I got from these guys doesn't work:
[link=http://www.sunnysidecorp.com/black.htm]Sunnyside Corporation[/link]

It appears that the S-L-X that you use is denatured exclusively with methanol without the ethyl acetate and/or methyl ethyl ketone. The latter is known to attack plastic.