Issues with smoke / fumes leaking out of the case instead of drawn out by fan

[jbv]

you should not have to use tape. Sounds to me like you are due for a thorough cleaning of the exhaust fan and of the air assist fan.

Cleaning the exhaust fan:

Caution: Dirty Pictures....or...How I Cleaned the Exhaust Fan

Update: 12/14/2018: Happily, the Glowforge crew has released an “easier to implement” cleaning regimen for the exhaust fan now…instructions for how to do it involve purchase of a special non-flammable degreasing spray cleanser and use of a special cleaning mode of the software…instructions here: Written up below is the old way that I was doing it…it’s a fairly labor intensive alternative that has worked very well if you are willing to keep up with it as you go along and not let it get …

Cleaning the air assist:

Cleaning Your Air Assist Fan (Performance Series)