Ovalized rollers: is there a less invasive remedy than replacing the entire strip?

What do you mean by precision? Have you tried checking the pins? Anyway, shaved hammers and ovalized rollers as a premise would lead to the replacement of the entire complete action; certainly, if the dimensions or weights are changed, it's a disaster... it seems like an easy thing, but I fear it is an intervention that only 1 out of 5 tuners performs well

To be precise, I mean that I find it a bit difficult to control the piano and forte.

The hammers that replaced mine were inadequate for my pF; the wooden core of the hammer head was not perpendicular to the escapement lever.

Unfortunately, ignorance (mine) and malice (others') come at a high price.

The diameter of the roller must be checked as it can affect the alignment in question. Furthermore, the distance from the hammer lever pivot to the core of the roller is decisive!!! It is almost always 17 mm, sometimes 16.5 or (exceptionally) 16.0. Therefore, one cannot use spacers different from those installed by the Manufacturer. Naturally, all measurements can be found. Or the roller must be replaced with an identical one. The hammer rail must also be suitable for that specific instrument model.

Thank you very much for this last piece of information.

It seems to me that there is no way to round off the ovalized rollers.

no