Coemar CF 1200 Hard Edge Instruction Manual page 30

2) Remove the gobo and its geared housing (E)
3) Insert the new gobo, making sure it is fitted correctly.You must ensure that the flat
support plate fits into its guide B and that there is a correct engagement between
the teeth of the cog of the gobo and those of the central rotation wheel's cogs.
4) Replace the gobo retaining ring (D) making sure it is secured in its catch.