The problem will not be a seal for the e-brake assembly or a block off plate. There should not be fluid in that area anyway.
The caliper piston has a shaft that exits through the caliper. This shaft is pushed into the caliper by the e-brake assembly to apply constant pressure to the disc. The e-brake block off just eliminates the e-brake assembly. However, the shaft from the piston still sticks out of the caliper. There is an O-ring that keeps fluid from leaking around the piston's shaft. That is what you will need to replace if in fact the fluid is leaking from that area.
There are other seals in the caliper that can leak as well but my experience is that the O-ring described above is the most likely candidate. You might also check you brake line. If the brake line is leaking fluid will escape, fun down the brake line onto the calipers, and can make you think the fluid is coming from the caliper.
I hope this helps.
'02 Cannondale Moto 450 w/updates
2010 RZR-S
'02 Nac's Cannondale Moto - sold
87 310R - mx equipped - sold
YFZ 450 - mx equipped - sold
416ex - mx equipped - sold
'86 250r - mx equipped - sold
'87 250r - mx equipped - sold
250x/350x hybrid - sold
lt250r quadracer - stolen years ago