Vert top motor...

You can get bushings for it too rather than buying a new motor. That's what my friend did.

To get the back seats out just press in the two buttons under the back seat between the seat and metal frame and they pop right out. Then unbolt the two bolts (8mm?) holding the backrest in and pull it out pretty sure. Motor is right behind.

I used brake fluid on my '90. Here's the process I used...

If you take the lining out of the trunk OR remove the rear seat you can get to the motor. Either way it's a messy ordeal. I think taking the seat out is easier.

There's a rubber plug in the motor resivor - take it out and position it so that it is at the highest point and all the air can run to it. Using a small funnel pour some fluid in that small hole. (put a rag underneath because some will spill) Plug the hole and then raise and lower your top a few times and repeat.

Good luck.

EDIT: If the motor is getting worn out, alternator shops can usually rebuild them or you can get a good price on a used/rebuilt one from eBay.