I think the number of people who would pay 1000.00 for a 16 year old Volvo with a bad transmission is really low.
We know there is 1 buyer for an 800$ Volvo
Not going to go with the car after further research. Most likely as I read, its mostly a clogged filter due to the failed torque converter.
Logic says somehow you need to check the fluid level and contaminants. If that looks OK, solenoids are sticking and possibly a pump pressure is marginal.