[edit]wth is going on with this forum? I've already replied, lol.] Sorry, somehow I missed your message (I don't recall getting a notification).
Re 1st question, I don't see why not, it's happening with the lead/copper bearings.
2. With the tin/alu/copper bearings, I'd say a very cautious and weak 'maybe'.
The problem is the babbitt isn't really meant to wear out, unless you're talking starship mileages! Lol, think 200k+
Also, we don't know how much babbitt is left even when no copper is showing. If it's a tenth of it's original thickness, could it still be safely embed any debris? Probably not I would think.
So atm it would appear the risk is less with the later bearings, but not down to normal (near 0) levels.
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Added another rubbed bearing link to the op, the poster, E90M3Ross from m3cutters's bearing hadn't gone through to copper
.