I wouldn't get too excited about those valves either. If they are not leaking you are fine. Do it at your leisure. it does not appear you have an "inherently unsafe" condition.
Just a note about gate valves and ball valves. Ball valves will leak just the same as gate valves. Where they leak is at the bonnet, in the packing. Most valves have a permanent nylon packing and not traditional packing gland material, found on larger valves. The problem with gate valves is that they do not get exercised often enough. Corrosion, and just plain old schmutz, gets in the bonnet of the valve and binds when you eventually turn it. Gate valves that are opened and closed regularly, and treated gently, will last a very long time. The major cause of failure is schmutz build up followed by forcing the valve handle. Ball valves, to a degree, eliminate the need for regular exercising, although it should still be done to keep the valve turning freely. They do not build up schmutz as much as a gate will.
The proper procedure for closing a gate valve is to close it until the gate just seats, then open it one half turn, and re-close. This will allow any debri under the gate to clear. Close it gently, always. When you reef down on a gate valve you will distort the gate or damage the valve stem. Leaking gate valves are usually leaking due to over-tightening or schmutz build up. Often, this can be alleviated by working the valve open and closed repeatedly. Remember also, not to force the valve when opening it. The gate valve delivers full flow at 25% of opening, so when you open it you want to open just until you feel a slight resistence. Cranking 'too open' can damage the stem as well.
Both ball valves and gate valves can leak from the packing nut. In fact, that is the most common area for them to leak externally. On the gate valve you should open it partially and tighten the packing nut, just under the handle, gently with a crescent wrench until it just stops leaking. Do not tighten further. The ball valve will leak from the same area. You must remove the handle to tighten the packing on it. It is not uncommon for them to leak there brand new from the factory. After the handle and flat washer are removed, you will see a bushing which is the packing gland, and you can tighten it gently. Over tightening the packing on either type valve is a receipe for early valve failure. It is not uncommon for either type to leak a little from the packing after you have exercised them. This is due to the fact that you are moving a valve that is not moved alot normally. Just tweak the gland a touch tighter.
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