Front Brake Overhaul

Hi all,

Last weekend I wanted to see what was wrong with the speedometer. Turned out it is the speedo-gear, there is my trouble. I used a electric screwdriver to turn the cable and i could see that the speedometer was indicating speed and the odometer started counting mileage. Next thing I tried to turn the wheel to check if that speedo-gear turns/rotates, but it didn't. Trying to turn the wheel (with my hands) I noticed that the Brake pads were a bit stuck and so I removed the brake caliper and then the brake pads inside. I pumped the brake leaver quickly and the piston started to come out of the caliper. It was dirty and quite stuck. I cleaned it with "Brake caliper cleaner spray", but my guess is that gasoline(petrol) would have done the same thing(cheaper method). On the clean piston I applied some brake oil/fluid and pressed it back in using a method seen on youtube(link bellow). After that i removed the old brake fluid from the system and replaced it with new one. I pumped out the piston again and repeated 2 or 3 times this procedure until the piston got loose. Brakes work fine now.
Still, the question remains: Can a speedo-gear be fixed, repaired, or should I buy a new one? And what is your opinion on Iridium NGK spark-plugs?

I got my info from these links, hope they are useful:

push the piston back :  https://www.youtube.com/watch?v=uA2K9PxDkDQ
How to bleed the brakes :  https://www.youtube.com/watch?v=P7jVI28x82U
How to clean the caliper :  https://www.youtube.com/watch?v=FNz00OTRLzM
This guy is just awsome(not that technical but funny)  : https://www.youtube.com/watch?v=C2uj1b8B3_o
Mr. Alexander make great GZ "How to ... videos" https://www.youtube.com/watch?v=_5pCfTXmdjo

GZ 250 service manual : http://dc417.4shared.com/doc/x8vqQ2bG/preview.html#bookmark16

Great Info

Regards