I dropped the sander and now it no longer works.

There are a number of reasons why a belt sander will fail to track -
Poor quality belts.
Physical damage (dropped).
Uneven wear of rubber drive roller.

When one becomes troublesome it can take a deal of sorting. Best idea if there is no obvious reason is to start by trying an OE belt.

The 4 1/2" 8 vac hole Hook & Loop back-up pads for the Ryobi Sander are no longer available, But you can apply a new hook surface to your present pad $3.75 each conversion disc at Supergrit abrasives , Gettysburg, PA 800 822-4003

Oil coming out of the sander indicates that too much oil is flowing into the the supply air. The rule of thumb for oiling an air motor is 1 drop of light machine oil per minute, per 10 cfm of air.

Part is no longer produced. I am going to adapt a 6" dewalt pad by drilling new mounting holes. (The Dewalt pad has 4 holes.)

Most commercially made disc sanders have replacements pads whether they are hook and loop type or the rubber. If you go to the manufactures web sit and look up your sander, it will usually be listed somewhere. But you might have to call an authorized repair center to find the part number to order.

are you putting holes in the papper with the guide? there has to be holes in the paper for the dust collection to work

This info may help;

Features: DeWalt D26451K 5" Random Orbit Sander Kit

• 3.0 Amp motor operates at 12,000 opm providing ideal sanding speed for smooth finish
• Textured anti-slip top & body grip provides ultimate comfort and control during prolonged use
• Controlled Finishing System maintains pad speed and minimizes gouging during start up
• Dust-sealed switch prevents contamination
• Sealed 100 percent ball-bearing construction provides longer life
• High capacity dust bag with built in vacuum adapter provides maximum dust collection with or without vacuum
• Dual-plane counter-balanced fan reduces user fatigue
• Accepts 5", 8-hole hook & loop paper allows sanding discs to be switched back and forth quickly and easily
• The sanding discs mate to the sander plate similar to Velcro, and this particular sander uses a 5" disc with 8 holes in it. Can be purchased in Home Depot, Lowes, etc....

Hope this helps!

Try lubracating the slide points with a light machine oil, little drops go a long way, ok!

* Are easy and economical to use. * Have fewer moving parts for longer wear. * Provide more power and torque than many electric-powered tools