If you remove the cover and flip the needle over the pin and it sits at zero it will almost certainly work OK. If it jumps up to some non-zero reading you can either subtract the zero reading or dismantle it further, either resetting the needle on the shaft (if it's removable) or resetting the needle gear position on the drive rack. Once you can see the bourdon tube and drive system, you need to force the tube closed until the rack comes off the gear, then rotate the (free now) gear to where it returns to zero at rest. Too much force on the tube will make it buckle and ruin it though. Some drive racks can be easily lifted off the gear making adjustment easy, usually on more expensive instruments though.
