I think my lens is weak, the cd has to be ejected and inserted a couple of times before it works

This is a rare problem ............ i faced similar kind of problem
i solved my problem with the help this repair guide you can also try this out i hope this will help you a lot .......
all the best
Click Here

Like any system, Xbox consoles require occasional cleaning to remain in peak condition. If you're experiencing skipping, poor sound quality, increased loading time, or any number of technical annoyances, simply cleaning your Xbox lens may correct the problem. The lens is responsible for reading all the data on your Xbox game discs; it is the most important part of the entire system. Cleaning the lens takes only a few minutes with the right cleaning product and know-how.
Difficulty: Easy
Instructions
Things You'll Need:

* CD lens cleaning disc

1.Purchase a CD lens cleaning disc. It is important that you buy a lens cleaner for a CD player, not a DVD player. Classic Xbox consoles are not DVD compatible, but they can play CDs. Some lens cleaning discs are marketed specifically as Xbox 360 cleaners, but these may not work in an original Xbox if the disc is DVD-formatted.

2.Turn on your television and Xbox just like you normally would to play a video game.

3.Open your Xbox's disc drive, placing the lens cleaning disc in the drive face-up. A lens cleaning disc works by sweeping small brushes over the laser lens surface. These brushes are located on the bottom of the disc; be careful not to touch the brushes---the microfiber brushes are delicate and can become damaged easily.

4.Close the Xbox and let the machine power up; make sure your television's volume is turned on. Your Xbox should automatically take you to the system's standard CD player menu. If this does not happen, select the menu manually using your Xbox controller.

5.Begin playing the first track of the cleaning disc. Listen carefully, because audio directions will play indicating the steps necessary for properly using your cleaning disc. Each brand of lens cleaning disc will have different steps, but they are typically very simple, involving tasks like skipping ahead to different tracks or briefly putting the CD in fast forward mode. If you cannot hear the audio directions, consult the written instructions packaged with the disc.

6.Remove the cleaning CD after you've followed the audio directions---a typical cleaning cycle only takes a few minutes, and the audio directions will tell you when cleaning is complete.

7.Carefully place the lens cleaning disc back in its case, avoiding damaging the brushes on the bottom. Lens cleaners can be used multiple times, so plan on using the cleaning disc regularly to help avoid future problems with your Xbox console