Jimmy2x

So I bought my first IROC last weekend and drove it to work for the first time last Tuesday. Shortly after arriving at work my wife calls to tell me that there is a red puddle on the garage floor where my car was. I get home to find that the speedometer housing is leaking. Put a new O-ring in and leak is fixed. Drive 26 miles to work the next day with no problem. On the way home the speedometer quits working. Get back under the car and find nothing wrong. Reassemble and take for test ride and speedometer works for 4 miles then back to 0. After some research, I am wondering if a complete seal kit with the retainer ring may be necessary. I am guessing that the old one is either missing or completely worn out. Could the gear piece be worn enough that the retainer won't prevent it from moving? Am I better off to get the new seal kit and a whole new gear piece as well?