"Dr Dons" jungle juice is a worth its weight in Naglers. Talk to Don at Bintel and he will set you right on the best way to clean your SCT optics (if at all necessary).
https://www.bintelshop.com.au/welcome.htm
As I'm sure you know, shining torches down SCT tubes is not recommended it usually causes you needless concern.
To ensure the inners of the SCT tube remain nice and dry and free from mould talk to Ron at Sirius Optics about the Far Point Dessicant Blocks for SCTs (yes, I declare I work there)
http://www.sirius-optics.com.au/farpoint.html
I clean my corrector every April 1st - yup April Fools Day, the day I also replace my smoke detector batteries and yes the corrector usually has heaps of crap on it from local fireplaces, dew (and I use a dew zapper) and who knows what and it comes up like new. You won't believe how incredibly filthy your corrector (or Newtonian mirror) can get before it starts to cause you issue.
PeterM.