Pluged rear main passage / Help

[davehc]

After reading many comments on rear main leaks , I still need advise . While doing a oil change on my "30" Town Sedan , my first[ oil change ] , since getting it last summer , and only putting a few miles on it so far , I'm not sure what to do next . It had the "regular" rear main oil leak , kind of bad also , so I figured I should do the oil change and make sure the rear main tube is not pluged . The tube looks good , but , while checking the return passage ways behind the valve cover , I found the back one , which goes to the rear main appears to be pluged . I have vaccumed all the oil out of it I can , and can only get a probe down about an inch into the passage .
Does any one have a trick for clearing this passage , or am I going to have to pull the rear main cap , and if so , am I correct in my reading of different posts , I "can" do this with engine in the car from beneath ? Any trick / how toos / what evers are welcome .
Thanks