We also have a 340RL, prior owner had for about 10 months. Not sure who did the caulk job on ours, but is ugliest caulk mess ever. I assume it was to fix a situation sim to yours. Some day i will be pulling that apart and re-doing it. So hoping someone has good tips.
Mine too leaked upon first use. I found no silicone caulking at the bottom of the inside of the track. I also found a seal void in the track at the end. Once I sealed the end void and the track inside the shower - all has been good.