C6 Trans Leak...

Trying to solve a small leak issue on my trans. At first glance I thought it was simply the trans pan gasket leaking. Cleaned up the area, replaced the gasket... still leaking. I think it may be coming from the round servo plate on the passenger side of the trans under the lines? Is this a common leak spot? I was looking into an upgrade that changes that produces a more positive shift between 1st and 2nd. Product is made by TCS. Is this a good idea with a trans that as far as I know has not been rebuilt?
I may get yelled at for this next question but here goes:HMMM:.... I was informed by a Ford mechanic ( old schooler) that running Merc 5 in these trans works really well. I have been running it for the last couple summers, everything seems good, shifts well and there where no real signs of badness in the pan... Is Merc 5 fluid too thin for this trans?

you also have your dip stick tube in that area .. little o -ring goes flat over the years ..and perhaps even the vent tube on top of the trans can spit out a drop or two now and then .. i dont know about the fluid thing ..

I ran merc 5 in a C6 that I rebuilt.

I dunno about running it in an older original tho. Might be a problem there.

check the cooling lines at the trans.

Check the modulator as well. Occasionally they will develop a leak.

Why run Mercon when Type F and FA are still available and usually at a cheaper price. Yes, I too have been told that it will work in my C4, but at several hundred dollars just for parts to repair, why chance something out of Ford specs unless a rebuilder requires it for operation.