1- Parker 21
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If there is no crack in the hood it might make a good writer. Otherwise throw it in the parts bin

. Anyway it may be a good pen to practice cleaning or nib smooth etc.
To clean flash the section by filling/emptying multiple times until the water runs out clear.
2- Eversharp model 707 $3.75.
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99% this is an
Eversharp Symphony. It probably works without doing anything. With a soft cloth remove the dirt/dust. Do not overdo it on the cap - it may scratch. Use a plastic polishing compound (like this from Thyphon's catalog) for the body. Check if it fills with water. If it does it can probably write unless the nib is bent/broken. They are usually excellent writers.
3- Lord Baltimore
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I usually keep the pressure bar and the feed from such pens. You might want to use it for practice. But you may want to practice repair on it since it is an inexpensive sample.
4- Stratford
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See 3.
5 - No name pen.
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See 3. Some people like this pattern.
6- Sheaffer snorkel
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This is probably a touchdown. Relatively easy repair but you need a proper sac.
Flash the section with an earbulb syringe or equivalent. Use simichrome for the cap and simichrome or a plastic polishing compound for the body.
7- Metal green marbled FP with gold colored clip inscribed: Eagle Pencil Co. U.S.A.
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Most probably like 3.
No 2 and 6 might justify as much as $40 for this purchase (since they are unrepaired and assuming that no major defect exists on these pen - missing tip, crack etc.).
Have fun!