help reducing the easter egg hunt on speedometer issue

Have M936, speedo will work for a bit and drop to zero, then reengage for a bit, then drop out, finally pulled out gauge panel to solve this and another issue, unhooked the cable from the gauge - unhooked the other end out of the transfer case. pulled each end, the cable does not appear broken, both ends look good (not rounded out). the transfer case end is leaking oil - very little but is wet on outside of speedo gear drive, also the rubber gasket on the cable flare is shot. I have greased the fitting a few times.

so question is what is the next step to figure out, is it a bad gauge or a bad gear housing or what not? need advice before I take off the gear drive at the case end (not overly sure what to look for other than a broken gear), or get a second speedo???

thanks for any advice.

Hook it back to the speedometer side and hook the other end in a drill and spin it. Have someone watch the speedo and see if has any fall off on speed when you can keep it as a good speed on the drill. Would be it's the speedo itself tho

simp5782 - ok did that - my battery drill will only spin the gauge to 20 mph, ran it for about 10 min, worked fine. will run the truck (once I get the front PM finished) and see if its really working or 20 is just not fast enough to get it to fail.
thanks

If they ingress dirty oil or dirt that causes it.
A strip down and clean does the trick. Getting them apart needs care though.

dmetalmiki said:

If they ingress dirty oil or dirt that causes it.
A strip down and clean does the trick. Getting them apart needs care though.

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do you mean the cable or the gauge or the drive unit on the t-case?