Your experienced staff is plateaued; many are not keeping up with new developments. They seem to lack motivation.
Short/medium term: Enlist the help of experienced staff to train and coach junior staff. Provide train-the-trainer and coaching courses. Give them training/education opportunities outside your organization to recharge their batteries.
Curriculum approach: Build a curriculum tied to a career path, so your staff knows that learning is tied to self-development. Work with Human Resources on developmental opportunities, such as the alternation of positions laterally between the field and administrative functions.
Class Act Inc. has addressed this and other training and curriculum problems with its clients. We'd be happy to discuss your unique situation with you. Click on Can we talk?