1993 Ford Escort shift/slip

Shifts ok when cold- stays in first or reverts to first when warmed-up. Will shift if I baby the RPMS but will slit out under stress(uphill or accelerate)
1.9L escort LX wagon

read about "accumulators" and also a relief valve located above the trans filter, and removable with an allen wrench, three of the four accumulators are located on top of the trans and accessible from exterior, the fouth is located in-line with the first three but on the face of the trans facing forward and just below the median line left-to- right, sort of south west looking at tarns from driver side