Transmission leaks: What can I fix without pulling it?

[86Gray300SDL]

My 86 300SDL has quite a few transmission leaks. I replaced the flex lines and that was the major one but it still has leaks from the bell housing, the right side banjo connection for the cooling line, and on the left side from the big plug with an internal hex. I think this big plug gives access to the front band piston or something to do with the front band. In the explode for this transmission I see two o-rings in that assembly. Does anyone know if I can pull that piston and replace the o-rings without problems? I plan to get some new washers for the banjo fitting and also replace the o-ring on the dip stick tube. Are there any other o-rings I should and can replace without pulling the transmission? I have a new pan seal and filter already.