Thought I'd share a quick tip for those that haven't seen this yet. Removing the delrin TT mushroom gears is can be difficult at times because of really tight tolerances. If you freeze the components for 10 minutes, the gears will fall right out! Delrin shrinks much more than steel when frozen.
When I need to replace my front mushroom gear I'll put the new gear and transmission in the freezer. Wait 10 minutes, old gear slides right out, new one slides right back in. Done! Same goes for the tail box.