165mm LS shutter synchronization question

After picking up a 90mm LS from ebay I spotted another auction for a

165mm LS that did not get much attention. I had only one minute to

either pass or place a bid. I chose to place a bid and I won at a

price nobody could resist it I believe. When the lens arrived I was

surprised by how nice the shape it was in. I remember seeing one at a

similar condition in a photo fair but at a price of $500+. Anyway I

got it really cheap and it looks really in a beautiful shape.

But when I compared it with the 90mm LS I immediately noticed a

difference. For both lenses to fire the leaf shutter, after cocking

them, you can just manually press (move) the aperapture linkage lever

next to the rear element of the lenses. Both shutters fire

accordingly. But I see a significant difference.

On the 90 LS when I press the aperature lever slowly I can see the

shutter blades closing down completely while the aperature blade are

closing down to the designated f stop. By further pressing the lever

the shutter fires and the shutter blades remain closed afterwards. I

can see the shutter blades closed fully before the shutter is

eventually fired.

On the 165 LS when I press the lever slowly and while the aperature

blades are closing down I do not see the shutter blades closing down

at all. In fact before the aperature reaches the designated f stop

suddenly the shutter is fired. The shutter blades close down quickly

and immediately open then close again (open for the duration of the

desigated shutter speed). Then the blades remain closed afterwards.

I am wondering why is the difference between the two LS lenses. Does

it mean one of them not working correctly? I wonder if the 165 LS is

supposed to work like that. I wonder if it will synchronize with the

focal plan shutter correctly. I guess I can shoot a roll and see if

it works or not. But it will take a few days before getting a result.

Can any of you who own a 165 LS tell me if mine is likely to be

problematic? I know I got it really cheap but it is because of the

auction. The seller said it is in excellent working condition.

The 90 is designed to fire on your command by any of the lens switches.

The 165 only fires with the camera shutter switch.