That's an older Alphax shutter. You might be able to partially resolve the problem by removing the front and rear glass then dipping the shutter in naphtha while cocking and firing the shutter a few times. Fire the shutter at all speeds but pay special attention to 1 through 1/15th. Slow shutters are usually caused by oil that's turned to gunk. Of course, this won't lube nor adjust the shutter but it will give you an idea as to whether a simple/cheap CLA will help vs. a major repair. Be sure to thoroughly drain, and blow out any naphtha then allow to dry inside on its side over night or in the bright direct sun 30 minutes each side to assure all the naphtha is gone.