While I was building I had an award winning builder suggested I not bother putting it in stating his was either nonfunctioning or unreliable. I did not put it in. Here is the logic.
You only really need to visually know where the trim is before takeoff. I turnaround and look. Therefore I KNOW where it is trimmed. I am not depending on a mechanical device which obviously can fail. If it can fail how much do you trust it? Will you feel the need to look back and check anyway? If you do, you did not need the device in the first place. Once flying you let stick pressure be your guide.
As a caveat, as I get older turning around to look is not quite as easy as it used to be. I still would not put it in.
If you can't get yours lubed and working - take it out.