No Backup. Data is not super valuable. I have been watching YouTube videos and while dust and debris is an issue there are electronic degreasers/cleaners and dust/lint free cleaning wipes that the Pro's use and so long as I were clean my work area, where a N94 mask, cover my hair, and where gloves I can eliminate a lot of this. Besides if I am successful I will immediately back the disk up.
There are two issues that concern me.
1st) If that I have a donor disk that is the same part number manufactured 5 months later than mine. This issue is that I have found out that it is possible the heads have microchip in them that has a driver. I can only hope that they did not change the driver from when my was manufactured and the donor was manufactured.
2nd) You need a head comb to hold the head from the platter when you remove and replace the head. Since there are 5 platers (4TB drive) you cannot get around this. I cannot locate any in the US. I found one on EBAY that is from China but I am not sure I trust and one from Servia from a Company that custom makes them out of aluminum specifically or that drive model number but it is around $100 plus another $100 to ship it FEDEX. I can use Servia's mail service but they even do not recommend this as it could take months.
This is why I have been going on the forums and running into this do not touch or the world will end mentality. Even after I inform them I do not care if I do not have success I want to try it anyway. Also, it is usually one person that always responds and after I research them they are usually connected to repair/recovery facility . Something fishy here. Sound like job protection to me.