When I look at 7Zap, that has now started charging for part numbers,
That caught me by surprise - and sure enough, when I've gone to 7zap just now they do indeed have the part numbers hidden as mentioned. I thought that this was going to cause problems (and still might in due course).
However, if you mouse-pointer over the wee magnifying glass adjacent to the part-hidden number, the complete part number appears in the URL readout on the bottom of the browser window (must be part of the link to the page for the part) - so you can still retrieve the part number. I am on a Macbook Pro using Google Chrome - I don't know if something similar can be done on other browsers or on phones / tablets.
I've just taken a screen grab to show this - my mouse was over the part 045****2P although this has disappeared in the screen grab, full part number appears in the bottom left hand corner.