If front seal = pump seal, the seal where the torque converter goes, it's an easy off / easy on seal. Use a pair of vise grips to pry it off and I just used a socket to help seat it.
Not sure what would cause that to just leak randomly, both transmissions on the cars I worked on had over 150k on them, and were 17 years old when the trans were taken out and the pump seals were fine.