scheirich cabinet---rollerball side rails---plastic end extenders and springsteel back mount

as stated, side roller arms, springsteel back, with plastic receiver sleeves connecting everything. problem! weight cracked 1 plastic receiver causing collapse. i need to replace the plastic ends, or the springsteel and plastic connectors. 17 & 3/8th between rails. the plastic connector is about 2 & 1/2 long, by 1 wide by 1/2 thick, and appears to adapt/adjust, the depth for irregularities in construction or installation. the springsteel moves the plastic/nylon adapters in as necessary. what i need is the parts so i don't need to rebuild the interior of the cabinet, that would speed the repair and make my wife ever so happy.