it was leaking underneath the washing machine tub

That would take forever to write in everything you have to do, but I did go to a website that had the steps you must do to complete the repair. You can google tub seal kit and mounting stem and the brand of your appliance and i'm sure you will come across the steps to complete the repair. I would advise you to first order a spanner wrench it makes the job much easier and you really can't complete the job without it. So do that first and then take the machine apart if you suspect it's a tub seal leak and then order your parts. if i had a spanner wrench available to me from the beginning it would have gone much smoother from the start.