I have an ALW 990, and am very familiar with your problem.

There can be many reasons for leaks, but given the age of the washer I'm betting you'll need a hub seal kit and hub bearing assy. (it seems they all do at this age). It's not too bad a job, but it does entail rather significant disassembly...

The instructions come with the parts, but I'll give you a quick synopsis, just so the Mr. can contemplate the project.

-remove cabinet bottom and front and loosen top (will need to be tipped back).
-remove agitator, drive bell (sometimes difficult) upper seal, 1-1/2" hub nut (I used an impact wrench)
-remove wash tub and hub - with some difficulty, and lower seal
-unhook springs, wiring and pump hoses (they will have some water in them - not too much. I put a small shallow plate under the pump and caught most of it)
-remove water level hose at back left of machine and fill hose, top center of tub.
-remove entire assembly - including motor and counterweight and place on floor in front of machine. This step is necessary to remove the 6 small bolts holding the outer tub to the motor frame. It may be possible to do this without removing motor assembly - but I thought it was easier out of the cabinet...
-remove outer tub and invert - the bearing assembly will now be accessable.
-I sanded/painted the tub base, as it had corroded and rusted...
-install new bearing assy, and replace outer tub and bolts.
-this is probably a good time to change the drive belt also (this requires either loosening the motor bracket or the pump to slip the belt through).
-reinstall tub assy onto base - ensure the nylon spacer is aligned properly.
- install new tub seal - specific instructions on part -
- install hub, spline washer and torque nut to 40-70 ft/lbs. This took more turning than I'd expected. I held the belt to keep the hub from turning, and put the lady of the house on the torque wrench - worked out great.
- replace wash basket (and probably lint filter if you have one)
- install upper seal - it takes a great amount of force to reseat the seal - use a large socket and make sure it's seated.
- replace drive bell, agitator, rehook everything and you're in business (the back two springs are awful (a vise grip helps, work from above).
- it's advised to spin the washer dry (1 qt of water to lube the pump) for one minute to seat the lubricants on the seals before filling with water.

Very time consuming, but you should have another 7 years or so. My original seal only lasted 6... last one still going well (I'm obsessing about checking for leaks now, though...) Good luck.