Removing the leatherette from a TLR is a delicate operation that must be performed with care. We're dealing with the appearance and value of the camera itself; therefore, leaving marks is generally undesirable.
The target is to leave the leatherette after the service in the same state or better. You shouldn't notice what part was opened. In this post I will explain how I do it and an example.
It's critical to know what camera you're going to remove the leatherette from and how it was previously glued.
Worst kind I have found are first Yashica Mats, almost impossible to remove it without spoiling it. I think from Mat EM and ahead it's more flexible vinyl already.
Ikoflexes and Super Ikontas (some are real leather) are made of vinyl threads glued together.
Rolleicord and Rolleiflex (till 3.5E2) use leather, T use strong vinyl and 2.8 GX and FX use a vinyl impossible no to leave marks on it.
These are the kind you will find most of the times.
The best practice with all of them is to use a sharp scalpel with really curved blade (old ones?) and drops of isopropyl alcohol or lighter fluid (never acetone) in the place we are going to skin. This will soften the glue underneath and it will make smoother our job.
One exception to this are Ikoflex or Super Ikonta, don't use any solvent or the vinyl will be teared apart in small threads. Only scalpel here.
The angle of the scalpel is very low, about 10 degrees so the blade goes almost parallel to the body. Always attacking the metal/glue with the blade so we can save most of the leatherette.
Careful with the inner part of the blade not to touch or leave marks in the outer rim.
Here a video skinning a Ikoflex IIa.
In this Ikoflex IIa case I went only for the screw positions. Lately with Rolleiflex and Rolleicord I go for the whole side. This allows me to clean the metal frame from glue residues and from the inner part of the leatherette.
To the metal frame I apply paint stripper (careful with the black enamel) and leave it for few minutes, removing it carefully with a plastic straight tool (not metal or it will leave marks), maybe two or more times is necessary for having the whole side clean.
The inner part of the leatherette I use small drops of acetone in the spots and then the scalpel almost parallel going for the glue, never the skin.
The whole process, let's say a winding side, can take up to 30 minutes easily but it allows me to leave it flat after gluing.
You may find the famous Zeiss bumps. The name is verdigris, formed over the years over the brass screws. Carefully remove the verdigris, first use gloves (tip, it's poisonous), cotton cubs with isopropyl and finally remove the small dust with a brush. It may happen that the leather has a mark from this verdigris; you can remove it (thanks to Mike Elek!). Using leather balsam in the inner leather (after cleaning it, of course! ), apply a small drop, gently spread it, and let it stay. If you need a second drop, it can be applied after 30 minutes, but I never had to.
Removing the leatherette from a TLR correctly is possible, requires lots of patience, focusing and steady hand.
After servicing the camera it comes the gluing but that deserves a new post.