I have it's bigger brother the 638 they are very similar. I'm not sure why you are thinking this needs to be fully stripped and rebuilt. Unless you can find a particular problem I would have thought a thorough check of everything would be a good way to go and deal with issues that come along.
A few ideas come to mind. Firstly make sure the beds are not cracked or distorted as if they are, and given they are an alloy, you should deal with this first as if you can't remedy the fault you could be looking to get a another machine as these parts are extremely rare if not impossible to replace. The bed adjusters are robust and would benefit from cleaning, freeing off and lubrication. After this set up the beds for flatness (look at The Wood Whispers YouTube video for setting up your Planner for guidance).
Remove the side casing and the gearing system will appear. Check, clean and lubricate the gears and chain. There are metal and plastic gears so be thourough in checking them for wear as these are the weak links in the system. Adjust the chain tension. This is the time to check the bearings for play and rumble in knife block - don't remove this if there is no reason too as it's a tricky job. Remove the knives and clean and free off the knife adjusters - a drop of oil on the adjusting Allen keys is sufficient.
Check the main motor drive belt and replace if necessary and adjust its tension. Whilst the belt is off check the motor bearings and it turns smoothly.
The thicknesser table has a central column and there is a handwheel shaft and gears to operate it. These may need a thorough decrease and clean then lubricate. Make sure it's easy to operate through-out its travel. Clean and polish the bed.
The above are the key areas to get right and unless there is a fault to deal with, all you need to do is inspect and service the components.
Otherthan cosmetics, make sure the electrics function correctly and the machine operates properly.
Finally install a new set of knives and you should be good to go.
Good luck