Pentair SpaBrite Fit

We have a connected spa (8’ diamter) with a Pentair SpaBrite light near bottom of spa. Light niche is mounted into the lower diameter wall (below the seat level). The lower wall is curved with a smaller radius that had made it almost impossible to engage the lower “tab” on the SpaBrite lense onto the grab fitting of the fixture (in wall) itself. Recently, we had the pool & spa refinished. With the additional thickness of the new surface coat, the SpaBrite lense cannot reach the tab to secure the lower part of the lense (light is fairly flush to wall, but affixed only with the top brass bolt. Difference is about 1/4 - 1/3". I recognize I could “chip away” some finish to allow the lense to fit further towards the in-wall niche fixture, but very concerned trying to chip the finish around the periemeter of the lense - may chip part of the finish further away from lense - which I want to avoid. Is there anyway to safely / carefully chip some of the finish from behind the lense - to allow the lense fixture to sit further back & allow engagement of the bottom tab ?  (Pebble finish pool / spa). Thanks for responses.