Furuno FR1500 Mk3 - Manual (Page 19)

2-3
Figure 2-4 Scanner unit, front view
13.Confirm that all screws are tightened and all wiring is properly mode. Coat
waterproofing gasket, bolts and tapping holes of scanner unit with silicone
grease. Check that the waterproofing gasket is seated as shown in Figure 2-5.
Close the scanner unit cover.
Figure 2-5 Correct seating of waterproofing gasket