It happens to everyone that they have to change the maintenance person for their garden for various reasons, but be wary of those who, without providing explanations, immediately say that "the sprinklers are no good" and then present you with the bill.
If your system is based on a studied and calculated design, before replacing or adding a sprinkler, it would be advisable to examine it. Usually, the sprinklers and consumption of each area are indicated in the projects. It is from here that we can understand if everything corresponds to reality or if changes have been made. The choice of sprinklers is never random, especially if made by a good designer.