Summary: Part 7 of 7 about why the painting in Tallinn is not a remnant of Lübeck's original painting from 1463.
The painting in Tallinn was restored between 1962-1964. In the process, the rest of Heise's claims were disproved:
During the restoration it turned up that the fragment in Tallinn hadn't been in so bad a condition that it would justify a paint-over - let alone being cut out. The paint-over was from the 19th century.
The restoration showed that there are no vertical seams (until the king) - in other words: If those 4 lines were in Lübeck in 1701, the rest of the painting would also have been there.
The restoration showed that the top of the fragment is intact (see picture to the right) - so the fact that there were pieces of canvas remaining in Lübeck actually proves that we are dealing with two different paintings.
Heise had tried to explain this away by claiming that the burghers of Tallinn had changed the text by painting it over - because they did not understand the "foreign" words. During the restoration the fragment was examined with X-rays and the unoriginal layers of paint and varnish were removed. These process showed that the text had never been altered.
Summary: It took time to disprove all of Heise's wild claims. But disproved they were.