Where to start...
Have the duplexer swept using a service monitor and a tracking generator.
Have the feed line Checked out using something like an Anritsu. Look at both return loss, and distance to fault. These tests will show what state both the antenna and feed line are in.
Question: why is the repeater going back to the factory? What brand and model is the repeater?
If the DB224 has a known issue with water, replace the antenna with one that will stand up to the elements and skip building a new phasing harness this will reduce the risk of further problems down the road.
If the phasing harness is toast, Replace the antenna with something like:
From Comprod:
Antennas - 870 Series VHF Exposed Dipoles Aviation (118-138 MHz) | Exposed Dipole Antennas | COMPROD Communication
Or from Sinclair Radio Labs:
Sinclair Technologies Online Product Catalog - SD214-SF2P4SNM(D00)
Either of these antennas are FAR more likely to survive water/elements simply due to having the phasing harness NOT exposed and taped to the mast. Heck, if water is an issue, put a rain cap on the antenna mast.
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