When it comes to replacing or servicing zone dampers or zoning systems, we need to look at the application rather closely and determine how the system works. This is much easier than most think. First keep in mind that names like "Trol-a-Temp", "Duro-Zone", "True-Zone", "Zone-First" and the like, are for the most part branded names. What we are mostly concerned with is the operation of said zoning system. For the most part, in residential systems, there are two basic types: Power Open/Power Close (3 wire dampers), and Power Close/Spring Return (2 wire dampers). There are some that communicate and modulate, and can be a little more difficult to repair or replace. Also be aware that there are some zoning systems that are a "Master/Slave" set-up, meaning the master thermostat controls the system mode (heat/cool) and the slave thermostats can only control temperature and the damper for its zone. Damper operation will be the same in these systems. 

In Zoning systems like Honeywell, their zone panels have always had zone damper terminals marked as M1-M4-M6. M1 has always been 24vac common for the damper motor, M4 for Power Open (PO), and M6 for Power Close (PC). Others will use 1-2-4, or 1-2-3 ect.  The Typical sequence of operation of these systems is as follows: When the system is idle and there is no call for heating or cooling, all of the dampers should be in the open position (unless the zone panel allows you to change this which is rare). If Zone one calls for heating or cooling, or fan, the unused zone dampers will be powered closed by the panel. If 2 or more zones call for heat or cool, those dampers will open. When the thermostats are satisfied, the dampers will typically remain open and the other zone dampers will open when the system shuts down.  

It is possible to mix-match dampers in most zoning systems, as long as you are aware of the damper and panel operations. In the example below, notice that zone one is a PO/PC damper, zones 2 and 3 are PC/SR.