Gutters are normally fixed on a slight slope, from 5-25mm in 3m, to ensure a good flow of water to the downpipe. If pools of water collect in the gutter then it is sagging and needs to be realigned by replacing the fixing screws and refitting the brackets. Fix a string line along the top of the gutter to mark the required slope. Drive a couple of strong nails into the fascia about 25mm below the gutter for support while it is being refitted. Take out the old fixing screws (if these are in the edges of the rafters you may have to remove a tile from the roof to gain access to them). Now release the brackets so the gutter rests on the support nails; tap wall plugs into the old screw holes and refix the brackets using new screws. Pack the gutter up to the required height with bits of timber placed between it and the support nails. Finally remove nails and string line.
Rust and cracks
Inspect metal systems for any signs of rust and clean back with a wire brush or, if you have an extension lead, with an electric drill fitted with a wire cup brush – this saves a lot of hard work. Now treat the cleaned areas with a rust killer. Fill hairline cracks with two coats of rust resistant primer. Fill definite cracks or holes with an aluminium bridge fixed in place with non-hardening mastic. Rub down with fine glasspaper. Corrosion is always worst at the back edge of the gutter and to repair this you will have to dismantle the system and treat each section separately.
Seal leaking joints in metal gutters with an epoxy repair material and rub down. If a leak develops at the joints of a plastic system, release the affected section by squeezing it at one end and lifting it clear of the adjoining length. If the gasket in the joint is sound, simply replace the section making sure the spigot end butts tightly against the socket of the adjoining piece. If the gasket is worn, scrape away all the old material and insert a replacement gasket or apply three good strips of mastic sealer in its place. Then press the two sections together again.