Old snipe trailers can be a mare!
It could have a few different types of suspension, a sprung plate under an u shaped section
(Although I have that on my sib trailer) or the more usual type like this which is the better one:
Mudguards and jockey wheels are cheap enough from gooutdoors etc.
But trust me, they can be a money pit to get them right and that's a trailer without breaks.
However, post a pic if you can and also look on ebay and see what else is about. a brand new trailer could be a really good buy for you.
What size is your boat?