I should clarify -
The 012 mod originated with Scott Dorsey so I refer those out.
While I'm not actively seeking out ML-52 mods I do have some booked in conjunction with 219 & 319 mods that I'll complete. These days I refer ML-52 mods out to Marik who is _the man_ when it comes to ribbons. He can re-ribbon and adjust tension - stuff I haven't done.
The 2500 would have to be more of a re-design / rebuild than a mod and really would not be a good price / performance mod to offer commercially. On the other hand, I've done so many 219 & 319 mods I'm in a real sweet spot with them. I can do them efficiently so both the clients and me are happy.
Part of the efficiency of doing these is knowing where the pitfalls are - you would be surprised how many emails I get asking if I sell capsules to replace the ones that got dinged when removing the HF resonance discs.