Bob-
In mine there is a sight glass that is built into a bolt. The whole thing unscrews and I put in an oil suction hose into the gearcase. Then refill– It’s a simple operation!

Rodd

Bob-

I recall unscrewing the bolt and capturing the gear oil and measuring it to put back the same amount that came out. All I did was drain and refill with oil. I didn’t clean out the gearbox as you are asking about.

Rodd

I could not see thru the glass–that’s why I added back the same amount I drained out, and it is working perfectly so far (5 years since the oil change).

Rod/Bob
It might be that there are different sight glass arrangements. Mine sounds as though it is like Bob’s. It is a horizontal plastic fitting on the side of the gear box and there is no way of removing it without losing about half the oil and then no way to put the oil back in to the proper level.
My Maxwell 1200 developed a seal leak between the motor and gear box last year and I could not confirm that I had sufficient oil by looking at the sight glass. The first thing I did was to talk to a Maxwell service rep and confirmed that the gear box had to be dismounted to add oil to the proper level. It was not practical for me to do that at the time so I stopped using the windlass until the boat was on the hard last winter before attacking the problem. While it is possible to dismount the gear box and motor together it would be a two man job and probably not worth the effort since it is relatively easy to remove the motor first. If I recall correctly, there are four bolts going up through the gear box from below that must be removed to drop the gear box. It is not necessary to mess with the snap ring on the shaft. Once removed one can simply pour the oil out, add new gear oil to the proper level (half way up the sight glass/plug) and reassemble. Not a very neat engineering job but that is the way it is.
Seals, if required, can be purchased as a kit (about $50.00) from one of the US reps listed on the Maxwell web-site. Those reps are not all created equal. It took me three tries before I found one who was knowledgeable, had the parts and was willing to tell me how to replace the seals.I replaced only the leaking seal between the motor and gear box and had no problem with reassembly.
Phil Fontaine

Hi Bob,
You are correct. Just remove the four allen head bolts.
I don’t see why your servicing plan should not work fine, presuming there is no feature inside the gear housing that shouldn’t be drilled. I’m sure you will be able to determine that when you remove it. I had never serviced mine (nine years) until I had the leak. There was a little gear wear but the remaining oil looked good and was still high enough to be providing lubrication (thopugh not visible in the sight glass). My unit is installed in the forward cabin and the leak became noticeable when it dripped on one of the bunk cushions.
Good luck.
Phil