Are they marked with a silversmiths mark on the back?
They actually appear to be plated and peeling so great care needs done to clean and not remove the shiny appearance...
I have used "NeverDull" wadding polish on one of my old saddles and it cleaned it, shined it and did not hurt the finish but there may be better products to use...you can purchase this product in any auto parts store where they sell the car wash/detail products and at places like Walmart too.
You must know though whether that is real silver or silver plating...
Since you already removed the corner plate you will not have leather to protect...just be careful you not scrub hard or run the risk of taking it all off the cheap metal it is attached to underneath.
Your plate looks very similar to the one I had...now sold that saddle.
I think I read here that some had used a clear nail polish to protect the them cleaned finish, again, great care to details need done with a gentle hand.
There are many old threads here about cleaning silver adornments on tack...some great tips in those old threads you can find too..
have cleaned the silver plate type on show saddles by going to Wally Marts, getting a silver jewelry cleaning cloth, and buffing, buffing buffing with it. It works and doesn't take off any peeling clear coat unless it's very very loose. In which case, you'll see tarnish under it and if you don't knock the loose clear coat off, you can't clean it.
Plated Silver will turn weird colors in the sunlight if any sort of polish is used. Then it's a vicious cycle, it dulls quicker, you use more polish, etc. The best way is a slightly damp cloth, rub over the silver, then a dry, soft cloth (I like a microfiber one) and buff it to a shine. Plated Silver treated like this lasts forever and looks good.
It will tarnish if it comes into contact with animal products such as leather and wool. Equally, pollutants in the air and on your hands (oils, acids etc) will add to the corrosion, as will dampness in the atmosphere, water, rain and sweat.
If you wash it, dry thoroughly but don't use rubber gloves or a harsh phosphate soap; buff with a soft clean cloth and if the tarnish isn't too bad use a gentle silver cleaning cloth which has anit-tarnish protection. Remember if you're removing tarnish then you're removing a layer of damaged silver and if you keep rubbing and using harsh agents, then you'll eventually lose the patterns and reach the lower layer. Some say that little and (reasonably) often, is better than attempting to remove severe damage.
I don't have silver on my tack but I've been involved with a Regimental silver collection for nearly twenty years.