I have a FED2 and a 4K and four lenses, two 50, 35, 85, 135. The 135 I never really use. All have been to Oleg (O.Khalyavin <firstname.lastname@example.org>, www.okvintagecamera.com) for CLAs. All came back in wonderful "brown paper packages tied up with string" (really!), smelling slightly of oil and working wonderfully. Have it cleaned and lubbed, remember about changing speed only after cocking the shutter and enjoy.