Have owned a dental practice for 6 years, before that managed several others. Turbine Source has been my go to for refurbishing hand pieces for a decade. The service is top notch (responses are within an hour or two, shipments come in a couple of days, and the cost is quite favorable). What used to cost me $1000s and several weeks to repair handpieces, now costs me ~$100 a handpiece and 10 minutes of my time. Turbine Source has saved me a fortune over the years. All products come with 'how to' manuals and warranties of all products (products always exceed the warranty periods by leaps and bounds).