tikkun torah (repairing a scroll)

The scroll in its mantle.

Despite the best of care scrolls will be fall into a state of disrepair. Atsey chayim (handles) will break, seams will split, holes, tears and rips will appear in the parchment and the ink will start to fade or lift away from the k’laf (something very common with the log (chalky) coated variety and cannot be used for the synagogue service.The sofer's job then moves on from writing to incorporate woodwork, needlework and patching. A scroll is very expensive and many have great sentimental value for a community, so every effort must be made to try to prevent them from being so pasul (invalid) that they are beyond rescue (economically or physically) and require genizah (storing away or burial).

The books of Bereshit (Genesis) and D'varim (Deuteronomy) have many faded letters that require considerable overwriting. 
This can often be more difficult than writing afresh.

The other three books also have fading throughout but because of very bad ink lifting overwriting may not work and they may need replacement from other parts of Sifrey Torah.

The worst section of scroll from the book of Shemot (Mishpatim) with extremely bad faded and lifting letters, now corrected.

The parchment adjoining the ets chayim at Bereshit has a large clump of hair which invalidates the sheet, according to most opinions.  Moreover the two rollers were joined to the parchment at each end with ordinary string, (now removed), instead of giddin (sinew).  There are also some loose seams.