The smaller of the two springs can break occasionally...However, it's not a common occurrence. I've broken one in about 40 years and literally hundreds of thousands of miles...
I also know others who have suffered the problem only once in many miles/years...I generally carry one in my spares kit if I am touring 'just in case'...Ian
Hello Chaps, on my bike 1st 2nd & 3rd are pretty OK to engage fourth can be hit and miss, especially if your trying to keep momentum going uphill, so if I'm reading this right if I shorten the the rod a little that may improve access to fourth?