Hello,
I am writing this as to help madgaz fix some of the glitches in this map, but until fixed, feel free to use the glitch.

Upstairs in the teleporter room, next to the box location, is a small "escape hole"
However this hole can be used for more than escaping
if you half exit the door and then slowly edge your way toward the catwalk you can stay on a ledge where many zombies cannot hit you

While in this spot I used a dead wire MG 42, a wunderwaffe, and had all perks (the most helpful being widows wine, electric cherry, jug and double tap for those who dont use free perka or perkalot)
This meant it was extremely easy to stay in this spot whilst killing zombies without much trouble of ammo.
Moreover, if you save a zombie at the end of a round, and you have enough points (which you likely will over round 10 using this strategy) you can just go and use ammo matic to refil your supply

Please address this issue when you next patch the game as to balance the difficulty.
Regards, Dark