Vanos... if you take it to BMW... they will replace it... it is always a good idea to replace that part.. because it is such an important part.. (I have replaced mine.. and it ran like a new car again.. quiet as never before)... I would just go a head and replace that sucker.. its worth it in the long run..
If your car is taking longer to start.. I would take a look at the starter.. and make sure all of your wires going to the starter selenoid are clean.. and fully connected... then I would check the voltage of your battery... those are the first trouble shooting ideas. Give that a spin or two....
Hope this helps some..
1997 E36 M3 1990 E30 325i