I've done it too -- Summar front cells come off easily, and as long as you mark the relative position of the front cell and the barrel, you should be able to get it back in the right position (as far as I recall -- it's been decades -- it was a multi-start thread).
Even so, I'd not recommend it. The flecks will do no harm: grease sputtered off the domed diaphragm, plus distilled lubricants, are another matter, and this is presumably what you had.
Nowadays, I'd be much more inclined to let Optical Instruments (Balham) do it, as they will return your lens as close to new as possible. They can even (single) coat it, if you aren't fussed about originality. Coated Summars can be very nice indeed.
Cheers,
R.