Replacing filter wheels

The filter wheels are replaced in an opposite sense of their removal. The fit on the central spindle is quite tight, however, and aligning the filter wheel in order to insert it on the spindle is difficult. Before the wheel will slide onto the spindle, it must be rotated about the axis to a specific orientation so that a pin on the central spindle matches a groove on the wheel. Once the wheel slides into place, it should be secured in place with the bolts (so have them handy as you hold the filter wheel in position).