Ruger trigger too light

First topic message reminder :

When I got my Ruger Mark III two years ago, I installed a Volquartsen sear and adjustable trigger in it. It had no trouble passing equipment control initially, but now, 10-15k rounds later, things have polished up inside and it's borderline. The trigger trips half the time in picking up the weight, and it releases every time if I position the weight lower on the trigger...

How can I make the trigger heavier by a few oz? Should I:

1. replace the sear and/or hammer with new parts?
   
2. replace the main spring with a new part?
   
3. make the engagement surface more coarse using low-grit stones?
   

Your suggestions are welcome...

And while I order parts, is there anything else that may be worth getting for a pistol going on 20k rounds? A new firing pin maybe?

I had a ruger mkiii replaced the trigger and sear with voquartsen ,put on a volquartsen upper and had a very accurate bullseye gun but it was still a ruger witch meant it was a pain to take apart and clean and had to be cleaned every 200 rounds or I would get failure to ejects. replaced it with an x-esse form larry's guns and couldn't be happier. 500 rounds through it already with zero issues and it is just as accurate.