Hi Chris,
Penny for your thoughts!
If its the model I'm envisioning, you need to remove the 2 vertical struts on the back of the panel (the ones used for wall brackets), the metal plate that traverses the top of the panel, then peel back the foil covering the top of the T-Con and remove the panel FFCs. The rest is obvious.
The rubber heatsink pads on these do ooze a liquid, but I've never found that cleaning this off has solved any T-con faults. Make sure you refit them...these T-cons generate some serious heat...have some muffins ready to go.
Bruce