Thw above post was last night. But now the shutter has gone for the most part right back to where it was in the first place. The speeds are close to 1/2 as marked.
That's why disassembling, cleaning and reassembling is preferred. If only blade mechanism is affected - i.e. shutter with removed blades works well - the whole procedure is quite easy and you don't have to disassemble the whole cocking and clock-work mechanism containing bazillion of elements. Of course - to determine this you have to partially dissemble the shutter, and if you do, there in no reason not to clean it. In my case (Compur #2) blades were accessible from the rear.