Here's a tip I got at the dealer today: If you don't have a tee, look straight down on the top of the Oslo and see the oval plate. Removing the oval plate gives you access to clean crud that falls when the chimney is cleaned. Looking at the oval plate, at 12 o'clock and 6 o'clock there are nuts inside the stove which hold down the oval plate. Remove these nuts, remove oval plate and you have access to vacuum out the crud.
The only warning was don't disturb the insulation which is right under the oval plate. Yes, there is a rope seal around the oval but removing the oval should not disturb the seal.
Quick edit: Re-install oval, tighten nuts before burning!
Shari

Quick edit: Re-install oval, tighten nuts before burning!
Shari