If the problem is with its picture linearity [Vertical], you have to enter its service mode to correct it. It is best to replace all the electrolytic capacitors [5 or 6] of it, at the vertical scan output circuit, before doing any adjustments, because, if there is any of it is damaged, the fault to this kind can occur too. After replacing it, just switch ON the set, and check the picture linearity
is correct. If not, enter its service mode, and adjust the vertical picture linearity. If you wish to get some details, check the site linked here.Pull up older posts.