Hi,  This is my third child and I have owned lots of mamas and papas pram/pushchair and travel systems. I have also sold alot of them too.  I have found that they tend to have problems in their own seperate ways:

The Ultima travel system:

What to look out for when buying, The xcel chassis tends to crack around the middle link bar causing it to sometimes break making the chassis very rickety and unsafe for baby.  This is easily recitified for free if under warranty or for £25 if not at mamas and papas.

Also whatch out for the hub caps as these tend to come off alot but these are only £2 for replacements.

The Primo Viaggio:

These need to looked at carefully under the covers as when you change the straps around for older baby they tend to break in between the strap holes, Again very unsafe for baby.

Pliko p3/mod/+/Pramette:

There are many of these sold and they always tend to break at the same point, the underneath crossbar tends to come out of the rivots and this is very unsafe for any child/baby.

The adjustable height buttons also tend to go missing but these are only £2 inc postage from mamas and papas.

They also tend to get easily damaged when posted around the very ends of the supports so please whatch out for this.

The zip on raincovers:

Well what can I say they are rubbish they tend to rip no matter how gentle you are with them. They always rip around the zip area so watch out for these too.

I have had many a pram from mamas and papas that have not had problems but I thought that most people would like to know what to look out for when buying second hand and even sometimes new!!