you'll need a chain whip to check the tightness of the last one or two cogs (if i recall i think that it is the second cog that tightens the stack, and the first cog screws into the second, but it may just be the other way around...). If there is no room to tighten the cogs any more you need a second chainwhip, so that you can unscrew the binding cogs from the body. The other cogs just slide on. Sometimes there is a washer under the stack, sometimes not. Sounds like you need one, maybe.