I’m contemplating doing a rebuild of the original Garrett T3 turbocharger on my 1985 300D (617.952) with about 220,000 miles. There appears to be an oil leak.

In picture 1 here, there is some oil that has collected at the base of the wastegate diaphragm. I have not been able to determine whether or not the diaphragm has a hole/slit. Picture 2 shows the diaphragm after I wiped the oil out. I didn’t see a hole/slit when inspecting the diaphragm:
1. With the wastegate depressed.
2. Using a magnifying glass.
Questions:
> Is there another way to check whether or not the diaphragm has a hole/slit?
> Could the oil be coming from further inside the turbo and simply leaking past the diaphragm?

As for the condition of the compressor impeller, it looks quite good (no visible nicks or damage) and there is very little play when I try to move it laterally with my fingers.

So:
Where might the oil leak be originating from?
After 220,000 miles and almost 38 years of service, is a rebuild in order?

I’d appreciate feedback about this. Thanks-

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