I have a bugaboo cameleon, now out of warranty. When I go up or down a curb the handle bar height estends. The white plastic clips used to hold the handle bar in place don't basically. Is there anyway to stop this happening or fix it?

The handle extension lever is held in by the pin it pivots on, cut the tip of a smaller size nail and use it to tap out the pin. There should be a rubber block and a matching steel shim under the lever. The lever pushes on the shim and the shim on to the rubber block jamming it against the handle. The steel shim is the usual problem. it slips out. Open the other side and use that shim to get a copy cut. A piece cut out of a tin can could work.