Warming them slightly to make them a bit more flexible and then bending them inwards? This might work if the saddles have loosened over time by being pushed on to hard.
I agree with Gordon! Use a hair dryer set on hot and lay the saddle on a wood or ceramic surface keeping it steady with an adorned leather glove. Do not let the appliance stay in one position for any extended time due to the plastic possibly melting from this action. Within a few moments depending on the amount of heat produced by the hair dryer, you should be able to squeeze the saddle sides together slightly to tighten them. Test fit the saddle while warm, & if it is tight enough, submerse in cold water to maintain the repaired position.
This is actually a great shot!!! Makes the klicky on the camel move naturally at the came'ls movement!!!
Hot Glue? It can be removed without damage if used sparingly.