Question on Wurlitzer 2510S Needle / Cartridge

I just puchased a nice working Wurlitzer 2510S. It plays fine, but I
suspect it's time to change that needle cartridge combination that's
likely 20 years old.

1. Should I change both the needle and the cartridge?
2. Is the correct needle the Pfanstiehl Diamond Needle 804-DS77?
3. Are there cartridge / needle upgrades from newer models that are
compatible that I should consider?
4. How often should you replace the needle?

One thing I noticed is that the needle brush is very stiff and seems
to be harsh on any needle. Is it supposed to be so coarse? Has
anyone made a reproduction / replacement needle brush for the
Wurlitzer? I also have a model 1700HF and it appears to be the same.

In case anyone is looking at these Wurlitzers, I was pleasantly
surprised. It's a nice sounding box with the ability to add two
remote speakers. It's likely one of the better looking stereo boxes
and was quite affordable. The one I found was given to a retiring
employee from a vending company in the late 1960s. He kept it in his
home until I purchased the juke and gave it to me with all the
original records. The inside is simply the cleanest I've seen on a
jukebox. Looks almost new. The only complaint (and this is minor) is
that it's only 100 selections and the mechanism isn't as visible as
the early models like my 1700HF.