I am with Ron - clean in situ, but spraying is a BAD idea. REALLY bad idea. Just get some cleaner from Bintel (or mix Windex with isopropanol - you can get it at the pharmacy or Bunnings - I get it from the solvent stores at work
). Radial strokes - centre out to edge - NEVER circular.
I cleaned the plate on the Mak and Mak Newt I had. The Maksutov was a breeze (though cleaning it revealed idiotic Chinese chinagraph/wax pencil serial/assembly number residue ON the corrector plate!), the Mak-Newt a bit of a headache since it is not a well sealed system and there was crud on the INSIDE of the corrector (I damned well don't recommend removing the corrector on a Mak Newt as it is a massively heavy chunk of glass!!!), but I managed to clean it off anyway through removing the focuser.
I have cleaned all my scopes. Never a single issue. I tend NOT to disassemble ANY of them - lesson hard learnt after shearing off a screw on an R200SS once (though I think the prior owner had cross-threaded and forced it in anyway) - drilled that one out.