Well, I rented a Praxis 8HP stump grinder last Friday and did the job myself. The machine was surprisingly easy to operate. It was about the size of a rear tine tiller. The Honda engine had more than enough power to do the job. You lock one wheel and pivot left and right to grind the stump while inching forward when needed. The machine never jumped, jerked or felt like it was going to fly out of my hands. My larger 24" oak stump turned into a 48" stump at ground level with all of the surface roots and such. It took me about 2.5 hrs to grind. I bet sharp teeth on the bit would have cut that time in half. The bit on that machine appeared dull to me. It takes some patience on hard wood stumps, but just let the machine do the work and you will be rewarded with lots of fresh mulch. We filled about a dozen garbage bags with mulch from that stump. My other two stumps took all of 15 minutes to grind for both as they were soft wood. It only cost me $50 in all for replacement fuel and rental fees to grind my 3 stumps. I would not hesitate to rent a grinder in the future vs. paying someone else to grind them.

The chopper is used to break down what material I want to compost. It does not take long to do. You can go as fine as you want. For kitchen material I even have use a large food processor. Good to grind egg shells. Once chopped up It is put in a Bokashi Bucket, in a large container or pile where I force air into it by a blower and a system of pipes. Once the compost is done I place it in a four wheel cart that has a bottom of expanded metal. I have a 12 volt DC vibrator attached to the cart that is used to shake the compost on the top of the expanded metal. Various sizes of the expanded metal can be used. Along with the shaking take a flat rake and push the compost back and forth. (GOOD JOB FOR YOUR SONS OR GRANDSONS) For yard waste I used an electric chipper shredder and grind the material as fine as possible. Also use the forced air system in the pile. Once done it is easy to sift. Always use the SECRET INGREDIENTS TO ENHANCE the Garden Gold.

Oleanders are usually removed by digging down 6 feet with a back hoe to prevent their growing back. Then monitoring for the few roots missed that will pop back up. But since your oleanders are dying, I'd just plant over them if you have taken them down to the ground. They will decomp in place providing an area for your new planting roots to push in and the claims of allelopathic effect of oleanders are unsubstantiated and having observed oleanders for decades I have never seen any such effect. They are quite toxic to people though.

I'm a little confused. If it's the upper burr ring that needs replacing, you definitely don't need to separate the grinder body from the base. You only need to remove the hopper and then lift out the upper burr ring straight up and out. To remove the burrs from the ring, you need to use a small screwdriver on the bottom tabs to snap them out. Then you can easily snap the burrs into the new ring. The Baratza web site has a trouble shooting section for all their models. They do have a document about how to separate the body from the base, but if I understand that you simply need to replace the upper burr ring, then you won't need to do this.