I just got my weights and spring in 2 days ago but I had a very hard time removing the stock weights , I pulled the set screws but couldnt get the bolts out that hold the weights, I wasnt going to beat on it any harder while on the sled and I didnt have the tools to remove it. I am curious to see how it goes with you guys, I just changed the spring and put it back together. I am debating on wether or not to send the weights back, after all the sled comes with 68 gram ad they sent me 68 gram but Im sure it matters how that 68 gram is placed. I just wanted to get rid of that bang upon engagement and get a smoother engagment , I want it to be able to crawl.