DT Swiss tubless valve issue

Last night I decided to get a head start on the new bike build and get the wheels setup. The wheels are brand new DT Swiss GR 1600 SPLINE® 25, and I planned on fitting the tubeless valves and some Conti Terra Trail tyres. Then leaving them for a couple of days to see if they held the air without any sealant.

I started with the rear wheel, but the tubeless valve wouldn’t insert all the way. It got to the point where I couldn’t press down any harder as it was hurting my thumb too much. So I tried the front wheel and the valve that came with that one went in fine, with a bit of effort.

This morning I had another go at the rear wheel, but still couldn’t get the valve all the way in. I then noticed that the rubber bit that is supposed to help seal the valve hole, was being split and pushed back on itself, almost like the valve hole is too small. I gently scrapped this off with a Stanley knife and managed to get the valve all the way in. Although it still feels like it wants to bounce back a bit.

Given that my previous tubeless experience was setting up the fat bike using split inner tubes, I have questions.

How easy is it supposed to be to fit tubeless valves into a rim?
I just expected them to drop in and then seal due to the lock ring on the valve tube.

Have I knackered this valve by shaving some of the rubber off, and should I buy a replacement?
What do I do if the same thing happens again? Do I need to burr the valve hole out.

First you could try if you can put in the valve with a rotary movement, like screwing the valve in. If this also does not work, you can check, if the tubeless tape was pushed into the valve hole. If so, just cut the tape out of the valve hole and try it again.

As long as the tubeless valve seals, you don`t have to replace it.

Thanks @wheel, I tried to screw it in, but I think the damage had been done by that point. I put a tyre on it last night anyway and it popped up nicely with just a track pump. I’ll find out this evening if it’s still up or not.

The shaved valve is fine, the nut squeezes the larger part of the rubber against the rim bed.