Hi @Lydia
We are not experts on matters of buying and selling here. From what I have read, however, when purchasing privately via sites like eBay and Facebook, buyers have a two-year time period to make a claim for any problems with the item they were sold.
If the item had an issue at the time of sale and the buyer was not made aware of it, the seller is then obliged to either replace the item, repair the item or return (at least in part) the money paid for it. In practice, this can lead to difficulty in determining when the damage occurred and trying to prove it was or was not damaged at point of sale.
The general rule is that the seller must point out any issues with the item when selling it. Otherwise, the buyer can at a later date claim for any such issues.
Here is a general guide to selling privately (German article via online translation):
https://***-advocard-de.translate.goog/streitlotse/internet-und-konsum/privatverkauf-auf-dem-flohmarkt-wie-steht-es-um-das-gewaehrleistungsrecht/?_x_tr_sl=de&_x_tr_tl=en&_x_tr_hl=en&_x_tr_pto=wapp
Best,
Éanna