1990 nissan pathfinder auto trans

I have a 1990 pathfinder that recently spewed trans fluid out of the front end. My mechanic said it was likely the pump oil seal and replaced it along with the torque convertor. He took it out for a test drive got about a block or two then no transmission response in any gear and no fluid leaking. Prior to this repair I noticed the trans would surge at higher speeds 55 or more aprx 500rmps. He seems to think that it is now the trans pump and of course another trans removal to replace it. So my questions are. Is this a likely cause of this problem, is there any other points he should check before removing it again. He said he was going to do a pressure check before proceeding. Thanks Respond to newsgroup only