Hi, sorry I have been off grid (work...).
The air filters are higher than the cover that needs to be removed, so access is either from the turret space or perpendicular to the cover, as I lack a milling device it would be the former.
The Crusader went together nicely, the only problem is the turret half joins, it needs to be perfect before gluing, as those rivets make post gluing clean up difficult.
More spare track pieces would be nice, Pinky's picture shows additional pieces.
There will be an AA one next.