My house has 3 stories, and from the first floor to the second it has spindles.
My issue with them is that they seem very rickety, and don't support any weight what so ever.
Is it possible to secure them?
The top set seem to be much worse than the bottom.
Stair hand rails are primarily supported at the top and bottom by the newel posts. While some additional support is needed in a span over 5 or 6 feet, the handrail does not need dozens of braces. You will often see an inside wall handrail with attachments that are several feet apart. The spindles are primarily intended for safety, to prevent someone from slipping under the handrail on an open staircase.
No spindles on a full handrail run would allow the rail to flex too much, so they are necessary. But if a number of them are loose, there is little likelihood of risk unless the attachment at the newels is also compromised.
Having said that, it makes sense to firm up the spindles. Driving 1 1/2 or 2" finish nails on an angle, pinning the tops and bottoms of the spindles to the handrail and the base should probably do it (much easier with a nailgun).
I know many times the spindles are only toe nailed in place. If this is the case you could pull the nails and use wood glue and screws. Make sure if you use screws to pre-drill the spindles or they will split.
You'll probably have to get a Carpenter or even a Stair Builder to fix your problems once & permanently. You can try the underside of the handrails for the solutions here How do I tighten/loosen this recessed nut and bolt? But, that will only fix the loose handrails & maybe the spindles.
If the Newel Posts at the ends of the handrails are loose, you might be able to drill-out round plugs to re-tighten them, the same as the underside of the handrails (if you had that). Otherwise, you might have to do something like this.
