I had accumulated quite a few modern large format lenses over the last 6 months or so, from local sales and the web auction place. These ranged from 65mm to 210 mm, made by Fuji, Rodenstock, Nikon, and Caltar. They seemed to be in nice shape but I was uncertain about the precision of the shutter timing, so I took them to a camera repair shop for testing.
The story was the same on each lens!! All seven! : Fast times were overexposed. Biggest problems were with 125 to 500, which were slow by 100% or more. Shop owner said that the mainsprings weaken with age and need to be replaced (if they are still available; many are not). Obviously this is a chronic problem even with lenses made since the 1970's. Somehow I had expected them to be a bit better than this....
Slow times (1 sec to 1/60) were good to exact.
The shop kindly charted out the times for each lens, and offered to repair lenses that they could get parts for. Rather than opting for major surgery I simply made tiny P-type labels and stuck them over the old numbers on the lenses.
The tests cost me $160 for 7 lenses (which cost me about $1500 total).
Now I know what I have here.
They also tested my Pentax and Soligor spot meters, which each were one stop off, but were easily recalibrated for $10 or so each.
So if you have any question about your gear, you can get accurate answers fairly cheaply. If you are like me, your gear is not as good as you think it is.