This is very similar situation that i have faced in recent past when i joined one of the project of Coal Mine in Jharkhand. 120 HEMM are deployed by the company for production but only 30 HEMM are in good condition for work and rest of HEMM stand in work shop for maintenance, furthermore, Every employee showing their attitude and don't want to work in organize manner, and only few employees have accepted and obey the decision due to this reason production down drastically. we worked out and implemented some good policies (which i have given bellow) after 3 to 4 month company was making profit from this project, and every one taking interest to work.
you stated in your problem that machinery has not be maintained by the technician on time, as you identified the root cause of non achieving the target, you just work on to motivate the existing workers rather hiring or taking any hard decision.
you should work on following points.
1. Do employee Satisfaction Survey (if there is any dissatisfaction, just work on it positively.)
2. Make the policies for career growth (like promotion, Job rotation, training Etc.)
3. Involve every line supervisor and Ask suggestion from Seniors Employee in Decision making Process.
4. Create a group culture work and should make one representative who can accountable and responsible (Reward and recognition give to all group members, if work complete in time or before time)
5. Always work on management by objective policies.
6. Train the Employee by showing Team work related videos
7. One day in every week fixed for meeting with every employee and understand their problem and give solution.
8. Create an environment that every employee feel as home.
9. in term of maintenance is concern (create a separate maintenance team (Only three employee involve )who can watch and supervise the all technician and their supervisor and sole responsible for all equipment in good condition for work., and also involve for preventive maintenance activities)
10. and lastly make working condition healthy and hazard-less ( Organized monthly meeting related safety and precaution)