My SIP air gun at work has half packed up!

It still spins round but has lost all of its power and it seems like all the air is just firing straight out the exhaust, I need to get a gearbox out of a car this morning, its a car i have never done it on before so its going to take me a while anyway let alone without my trusty gun!

Please help if you can,
It gets oiled regularly before you ask!
Cheers
COl

taken from else where -

If your impact wrench is not working like it used to, there are a few things you may check before you throw it in the dumpster. If you are experiencing low power on your air impact wrench, here are three easy steps. The first problem could be a dirty inlet bushing or air strainer screen. Just simply clean both of these with a suitable cleaning solution. Next, examine the cylinder. Replace it if it is worn or broken or if the bore is scored or wavy. Finally, disassemble the tool and clean all parts with a suitable cleaning solution in a well ventilated area. Reassemble the tool according to manual. These three easy steps can solve low power problems most of the time. If your impact wrench is not impacting properly, try this. Check and make sure the air tool has been properly lubricated. Lubrication is absolutely critical to maintaining your air tools at peak performance. To resolve lack of lubrication, remove the hammer case and lubricate the mechanism. Once the hammer case has been removed inspect the impact wrench mechanism parts. Replace any broken or worn parts. Most manufacturers include detailed instructions on how to do this procedure in the manual. These are a few easy procedures that can extend the life of your impact wrench and restore it to its original working condition.

As an apprentice (ie a while ago hence lack of detail now), i had an air tool to fix. Turned out to be sticky vanes. By cleaning the vanes and cylinder etc it worked OK afterwards. Having the air being exhausted certainly sounds like it could be vanes to me.

mine done ther same thing with the sticky vanes too..

also had one drop power and was ready to throw it in the bin till i discovered the coupling on the air line had gone funny inside and wasnt puttin full pressure through..