Welcome to the Community Cyclop:
It would be less trouble, expense and harrasment to change the plastic pan.
Not knowing what position the unit is in, I'll give you 2 answers that work the same way. For a horizontal unit in the attic; remove 4 screws along each side (two at each corner) use #9 galvanized wire to make a lifting loop between each pair of screws, rig it with rope on each end that can be put in a come-along hook in the center, attach the come-along to the rafters above and ratchet the load up. It will lock in place and hold it out or your way while you make the change.
For a vertical unit; do the same lifting loops at the 4 corners on the top and connect the come-along to the joists above and lift the same way.
If I am WAY off base here we can talk some more about it.