A method for exchanging a portion, more especially a damaged portion, of a plastic component, characterised by the following steps: - separating the portion from the plastic component, - providing at least one connection element (4a, 4b) made from a plastic, - pressing the at least one connection element (4a, 4b) against the plastic component such that the at least one connection element (4a, 4b) comes to bear against a remaining part of the plastic component, - causing the connection element (4a, 4b) to vibrate by means of an ultrasonic sonotrode and welding the connection element (4a, 4b) to the remaining part of the plastic component, - providing a portion that replaces the separated portion, wherein the replacing portion has a hole, more especially a through-hole, - mounting the replacing portion in the region from which the separated portion was separated, in such a way that ∘ the replacing portion is clamped by means of its hole directly onto the connection element (4a, 4b) with a form and/or force fit, and/or ∘ the connection element(4a, 4b) extends by at leasta defined amount through the through-hole, wherein a clip element is clipped onto a portion of the connection element (4a, 4b) that extends through the hole, wherein the clip element projects above the through-hole and connects the replacing portion to the remaining part of the plastic component with a form fit and/or force fit. - separating the portion from the plastic component, - providing at least one connection element (4a, 4b) made from a plastic, - pressing the at least one connection element (4a, 4b) against the plastic component such that the at least one connection element (4a, 4b) comes to bear against a remaining part of the plastic component, - causing the connection element (4a, 4b) to vibrate by means of an ultrasonic sonotrode and welding the connection element (4a, 4b) to the remaining part of the plastic component, - providing a portion that replaces the separated portion, wherein the replacing portion has a hole, more especially a through-hole, - mounting the replacing portion in the region from which the separated portion was separated, in such a way that ∘ the replacing portion is clamped by means of its hole directly onto the connection element (4a, 4b) with a form and/or force fit, and/or ∘ the connection element(4a, 4b) extends by at leasta defined amount through the through-hole, wherein a clip element is clipped onto a portion of the connection element (4a, 4b) that extends through the hole, wherein the clip element projects above the through-hole and connects the replacing portion to the remaining part of the plastic component with a form fit and/or force fit. ∘ the replacing portion is clamped by means of its hole directly onto the connection element (4a, 4b) with a form and/or force fit, and/or ∘ the connection element(4a, 4b) extends by at leasta defined amount through the through-hole, wherein a clip element is clipped onto a portion of the connection element (4a, 4b) that extends through the hole, wherein the clip element projects above the through-hole and connects the replacing portion to the remaining part of the plastic component with a form fit and/or force fit.