The crystal on my 195 was also dirty, and I had a hard time cleaning it, while it was pressed into the case.
I ended up removing the crystal from the case, cleaned it, then pressed it back onto the case. Pressing the crystal back on, is not as hard as it looks.
Buy a good tool, and you should be ok.
At the same time, when I had the watch apart, I also greased all the orings, and replaced the split oring in the crown tube.
The watch is water resistant enough, I used it sailing and swimming this whole weekend, in and out of the ocean without a problem.