On my cheap chainsaw the guide blade for the chain delivers the oil - I think they're all much the same - also the blade needs to be reversed from time to time to even out the wear.
If you remove the blade you will see oiling holes that sometimes get clogged up with wood debris - similarly the running slot - all need to be cleaned out.
One of the holes will rest against a small hole in the chainsaw body to drip-feed the oil - the delivery hole can sometimes get blocked with wood dust.
Here's a link to a 12 page pdf about sharpening chainsaw chains - page 5 mentions oil issues.
http://www.stihllibrary.com/pdf/SharpAdvice061301final.pdf
Good luck...
Peccavi, May 2010
