Lead in oil sample

if the paint is disolving off mixing in with the oil the oil will result in a colour change.
your oil sample should show this visually.
now brass does contain lead, copper, etc...
also a spectrograph really only picks up wear particles (burns) usually only up to say 5 microns in size, 7 microns max..
a spectrograph is good for depicting historical wear in my eye.
what i mean about historical wear is that any larger wear particles have ended up broken down over time to smaller and smaller pieces.
routine particle counts should make your base trend, at least once a month.
if your particle counts show increased rate of wear.
then resort to further tests.
if there is something going on try a ferrography (a snap shot) of all pieces big and small.
ferrography is usually better for metallic wear particles, however there are tricks that they can do to capture non-metallic wear.
also you can do a wear debris patch test, sort of same idea, just no magnet and not as clear of picture.

good luck!

Paint in oil samples usually ends up showing titanium in metals testing. If the lead is coming from a brass alloy, I would expect no higher than the copper count to show up, and usually less than that.

Do you use synthetic oil in this piece of equipment? We recently changed the oil in a pump to a synthetic Diester oil and for some reason the oil was getting milky within a day or two. It was determined that the synthetic oil attacked the paint on the bearing housing and this contaminated our oil. We switched back to the mineral oil (that we originally used) and the problem was resolved.