Rain Filter / FTC Control

We are using a 48" Super HD array with e127/125 series MFDs. We are finding the Rain filter ineffective other than possibly a small effect on the inner 1/3 of the screen around the boat, and there does not seem to be an FTC control. We are typically operating in Harbour preset mode with a range of .75 to 3.0 miles and have found the only way to paint a useful picture in rain/snow is to manually reduce the gain, with the related risk of loosing targets. In the e-series MFD manual there is reference to an FTC control for the non-HD digital radomes but not the HD or Super HD radomes or open arrays. Is there a way to penetrate rain showers in the outer 1/3 of the screen, as an FTC control would do, without reducing gain?
Thanks,
Ian