Locomotives kicking abruptly sideways by the check rail just didn't look good so I made a simple solution -
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A short length or rail, slightly curved and filed to a point. Some 'builders adhesive' holds it in position and all locomotives now run through smoothly. It probably doen't need to be that long but glueing to 3 sleepers gives the strongest bond.
You can often see the damage to the start of the LGB check rail where the wheel flanges have knocked into it. Perhaps they wear down with use?
Back to the original problem.
A most important consideration would be that the point and the adjacent tracks have to be completely flat. There must be no twist in the rail heights.
Many people recommend using a spirit level for checking but I prefer to use a flat board of about the same length as the rolling stock. Using a board will check the whole area of the point much better than a spirit level. If it doesn't rock at all that is good but most unlikely. A rocking movement of 1 mm corner to corner (which is the maximum of what you need) would be hard to detect by using a spirit level. Use a spirit level in conjunction with a board.
Not sure about your track base but the tracks can settle over time and what was a perfectly level track can develop derailing issues so definitely worth checking.
Alan