[Yaesu] FT1000MP RIT frequency jumping - optical encoder is broken?

[Rimantas Baltusis]

Hello, reflector
I have been using FT1000MP since 1998. Recently I found that VFO frequency is chaotic jumping several kc then I rotate RIT knob. There was no any mechanical impact.

A few years ago a similar subject was discussed on this reflector. Some hams pointed that it was likely RIT optical encoder  broken and the only way to cure this problem was to replace it. 

My questions:

1) is it really optical RIT encoder broken? what otherwise?

2) is it impossible to repair RIT encoder at home?

3) does anybody can explain where I can buy (order) this specific part? My search on internet is fruitless. A local ham's equipment dealer have never heard about such problem.

Tnx, 

Rimas, LY2BM