[V6-12v] Heater Core Kaput

[Wilfried Link]

Anyone ever DIY replace the heater core on an A6? Mine
is flooding the footwells with coolant and steaming
the windows furiously. I have the Bentley manual,
which makes the removal of the heater box look fairly
straightforward, but repositioning the flaps inside
the heater box after replacing the core looks fraught
with danger without the VW/Audi special tool template
(about $70 and a 7 to 10 day delay to get it.) Any
experiences out there? Thanks in advance.

Wil Link
1995 A6 Avant